When Should You Use a Double Ball Valve in a Pipeline System | Common applications in oil, gas, and chemical lines

Double ball valve suitable for needs double isolation’s working conditions, like oil gas conveying pressure ≥4MPa or toxic medium pipeline, often used for maintenance venting and anti-leakage scenes, suggest middle cavity sets discharge port and regularly detects leakage rate ≤0.01%, installation time ensures two valves spacing ≥1.5 times pipe diameter in order to maintenance.

oil and gas service

Absolute’s physical isolation

Run to North Sea that side’s offshore drilling platform look one eye, water surface downward 1500 meters deep’s place, black’s crude oil exactly with per second 8 meters’ speed in pipe inside madly running. Pipe inside’s pressure all year round soars to 10,000 psi, roughly just like 700 atmospheric pressures dead dead pressing on iron sheet on.

Only rely on one layer 50 millimeters thick’s plastic sealing ring, encounter clamping sand’s high pressure oil randomly rushing, use not long just will scrape out tiny’s scars. Double ball valve belly inside one by one stuffed two pieces 400 kilograms heavy’s solid big steel balls.

Two pieces steel balls surface all plated one layer 0.05 millimeters thick’s hard’s tungsten carbide. Worker once twists rotary plate, head one piece big steel ball turns a 90 degrees takes road blocked dead, forcefully takes 120 degrees’ boiling hot crude oil blocked at outside. Crude oil strength big, desperately along gap toward inside drills.

Leaked past a little oil water, all dropped into two pieces steel balls middle that 0.5 cubic meters’ empty gap inside.

• Leaked in’s oil drops along small thin pipe downward flow
• High pressure gas relying on gap all of a sudden scatters run away
• Pipe on’s pressure gauge accurately points to 0 psi
• Nose-piercing’s hydrogen sulfide smell drops to 10 ppm below

Middle so one leak one relax gas, second piece big steel ball basically just suffers not to any impact force. Just at leaving valve backward not reach 3 meters far’s place, electric welder brother just took off thick heavy’s explosion-proof suit, exactly preparing take angle grinder cut open that root 36 inches thick’s carbon steel pipe.

2500 degrees high temperature’s electric arc sparks eye looking just will everywhere randomly fly, this pipe inside even if left a tiny bit’s combustible’s methane gas, even if raised a little weak’s static electricity, all can detonate equivalent to dozens tons TNT explosive’s fireball.

Run to minus 46 degrees’s Alaska ice sky snow ground inside send natural gas, ordinary’s rubber ring frozen till like glass same brittle, lightly one touch just shatters into dregs downward drop.

Surface roughness only has Ra 0.1, lets two pieces metal tightly fit ground paste dead together. Factory building inside doing water pressure test’s time, big water pump one effort ground toward closed tight’s one head hits mixed fluorescent powder’s pure water.

• Add pressure continuously adds to normal times used’s 1.5 times
• Dead dead support pressure stare full whole 30 minutes
• Exhaust port below pads one piece pure white color’s filter paper
• Take checking money that kind purple light lamp everywhere shines one pass
• White color’s filter paper even one little water spark all not stick on

Worker two hands holding 1.2 meters long’s big wrench, must use out 800 Newton meters’ ruthless effort just can take first path ball door close up. Inside’s gear takes strength amplify three times, little by little takes heavy’s big iron rod downward press. Only taking door close up still not okay, pipe thermal expansion cold contraction up pulling people’s strength big very.

Big summer sun one shines, 100 more meters long’s high strength steel pipe can grow long quite a few centimeters, pulls out 50 tons’ thrust dead dead topping against joint. Belly inside’s two pieces big steel balls up down two heads, all are by big thick iron stick firmly fixed dead at middle.

Oil water rushes over’s heaven big thrust, all along iron stick passed to 80 millimeters thick’s thick solid cast steel outer shell on, steel ball itself absolutely still, one bit not toward backward’s sealing seat on press. Operator normal times works, presses two times machine room buttons, not reach 20 seconds pneumatic motor just takes two paths big doors respectively switch properly.

Pasted at pig iron outer shell outside’s sonar detector, twenty-four hours listening to inside liquid rubbing pipe wall’s fine broken sound. Natural gas running up one second can dart out 20 meters far, high high low low’s sound signals continuously transmit back to monitoring room’s big screen on.

Sealing’s place even if cracks open one strip even 0.1 millimeters all not reaching’s hair thread gap, computer screen on’s sound wave graph 3 seconds inside just will violently shake. On duty’s person one pats red color button immediately cuts off gas supply. Along iron frame climbs up five floors high’s place daily patrol.

• Opens small opening toward inside squeezes new’s sealing oil
• Looks looks middle pressure relief valve’s nut loose not loose
• Uses recording pen records down open close door time iron rod friction’s sound
• Stares one eye hydraulic cylinder inside’s oil still left how many milliliters

Run to Middle East big desert middle’s gas extraction station, outside is 60 degrees high temperature’s violent exposure, pipe inside two pieces quite a few tons heavy’s big iron balls quietly without sound ground take gas road dead dead blocked. Inside all is corrosiveness big till scaring people’s sour gas, two pieces thick iron doors take those taking life’s gases imprisoned at middle that little narrow gap inside.

Space & Weight

One long 300 meters, wide 60 meters’ floating production storage and offloading vessel must at sea on float whole 25 years not return to dock repair. Up above densely packed stuffed full large scale oil water separators, dehydration heating furnaces and tens of thousands roots thick thin crisscrossing’s metal pipelines.

Left for pipeline valve installation’s gap narrow cramped, even a wearing thick heavy life jacket’s fat young man all very hard squeeze in. Past in order to reach two paths valves double insurance’s safety standard, factory inside must take two units thick strong’s single body ball valves making do assembling.

Two units independent’s big iron lumps middle, must weld on one section long reaching 1.5 meters’ carbon steel short pipe to do connection buffer. One set 12 inches caliber, pressure level reaching Class 1500’s traditional splicing valve group, overall length exceeded 3.2 meters.

Equipment total weight soared to scaring people’s 6.5 tons, almost equivalent to two heads adult elephants’ body weight dead dead pressing at below’s steel structure bracket on.

Sea on operation rents one vessel carrying 500 tons crane’s engineering ship, go out to sea work one day work’s rent starting price up to 200 thousand US dollars. Hoisting 6.5 tons’ huge monster time, sea wind only blows a level 6, suspended in mid-air’s steel iron monster just will in mid-air violently shake.

Operator slightly not paying attention lets iron block hit to side’s load-bearing column, whole piece area’s pipe network layout plan just must all push down newly come. In order to support two units big valves’ huge weight, below’s load-bearing I-beam must from original’s 20 millimeters thicken to 40 millimeters.

Oil conveying main pipeline along line if install on 20 sets splicing combination, only is reinforcing base used’s steel material just must extra consume away whole 80 tons. Take old style big valve change into integrated style’s double ball valve, on-site’s working environment immediately changed a big appearance.

Making equipment’s master takes two pieces heavy’s solid big steel balls, forcefully stuffed into one long merely 1.6 meters’ overall cast steel outer shell inside. Original 3.2 meters’ occupying land length, one shrink only left original’s one half not reach.

Whole iron lump’s weight from 6.5 tons plummeted to 2.9 tons around. Working time deck on one unit loading weight 5 tons’ ordinary small scale crawler crane just can easily take it hoist into narrow’s pipeline vertical shaft inside.

Simply take a notebook finely calculate one pen account, change on integrated forging‘s new equipment in the end can save down how much real’s manual labor and materials.

• Nut using amount large margin reduces, thoroughly said goodbye to splicing short pipe two ends that densely packed’s 48 pieces high strength M36 big screws.
• Gasket aging leaking gas probability following downward drops, flange joint amount less a half, running popping dripping leaking’s failure times cliff style falls.
• Daily removing rust brushing paint’s maintenance surface area shrank near 40%, maintenance worker carrying 15 kilograms heavy’s paint bucket less climbs two layers scaffolding.
• Pipeline overall vibration amplitude weakened about 15%, weight concentrated after metal base again also will not be pressed till creaking sound.
• Purchasing logistics expense following saved one big amount, loading standard container sending sea shipping time carriage inside can extra stuff in quite a few units equipment.

Below this piece table takes two sets plans’ family bottom flipped till clearly:

Valve comparison parameters (12 inches Class1500)	Traditional two valves splicing plan	Integrated double ball valve	Reducing burden actual effect
Pipeline total length occupation	3.25 meters	1.62 meters	Length shortens 50.1%
Single set equipment total weight	6520 kilograms	2980 kilograms	Weight lightens 3540 kilograms
Flange tightening connection places	4 pieces	2 pieces	Leak points reduce one half
Hoisting and docking consuming time	14 hours	4.5 hours	Time saves 9.5 hours
Load-bearing support bracket cost	About 1.2 ten thousand US dollars	About 4500 US dollars	Expense shrinks 62.5%

Main pipeline became short, left for workers walking patrolling’s iron sheet aisle fully spacious nearly 1 meter.

Before patrolling time always must turning sideways body pasting 120 degrees boiling hot’s insulation layer difficultly rub past. Two hands carrying filled full wrenches’ heavy tool box, swaggering just can along widened’s channel big steps toward front walk.

Outer shell on lacked messy’s flange plates and protruding’s screw heads, giving pipe fittings wrapped on ultra fine glass cotton also became handy much. Originally wanted take big scissors cut out 12 pieces different shapes’ asbestos tiles one piece piece splice paste up.

Worker takes 4 big pieces thickness 80 millimeters’ fireproof blankets toward on one wrap, pull tight outside’s iron wire net several minutes just can work finish work. Less install two pieces flange plates, at main road on less buried two pieces all year round leaking gas’s big minefields.

Every interval half year do one time high pressure pipe network measuring leak, inspector holding long reaching 80 centimeters’ electronic probe at metal seams inside one by one sweep. Check one place carrying 24 pieces screws’ old joint just must consume on fully 20 minutes.

Take flange joints chop off one half, one trip pipeline patrol walking down helps shift group save down 3 hours’ blowing sea wind time. Bumping into level 12 typhoon day, platform on all outside operating workers all must evacuate to explosion-proof safety cabin inside hiding protecting life.

Mad wind rolls up 10 meters high’s big wave ruthlessly slaps on lower layer’s sewage steel pipe on. Double ball valve shell thickness reaches 75 millimeters, whole body receiving force even till like a smashing not broken’s solid iron walnut.

Relying on long bolts forcefully spliced up’s old object, is by thousands tons’ sea water fiercely one hit. Middle that section long short pipe two heads’ combining part accurately will shake out naked eye fundamentally cannot see’s tiny dislocation.

Sea water inside up to 3.5%’s salt content along that strip 0.05 millimeters’ fine gap dead life toward inside drills. Not out three months time just can take inside’s high strength alloy bolts bite out one layer thick thick’s iron rust red.

Anti-corrosion primer at rusting’s place into pieces bulges peeling off, only can wait sky clear hired people take coarse sandpaper newly polish put on paint. One whole big iron block firmly welded at 36 inches’ main pipeline on.

Letting typhoon how madly blows, thick strong’s pipe network steadily not at all shaking. Design institute drawing blueprints’ engineer, again also not need for extra out’s dozens tons scrap iron go desperately thicken below’s supporting pillars.

Following international standards

Workshop empty ground on placing dozens units just from production line pushed down’s double ball valves. Wearing yellow color safety helmet’s inspector hand inside gripping one book thick thick’s American Petroleum Institute API 6D specification guidance manual. Every one unit leaving factory’s big iron block all must at white bottom black words’ notebook on one by one crashing barriers tick.

Normal times pipeline inside’s crude oil pressure at most runs to 1500 psi. Water pressure testing workshop’s booster pump unit crazily roaring, forcefully toward closed’s iron cavity inside pours in 2250 psi’s high pressure pure water. Whole exceeded rated working pressure’s 1.5 times. Dial face on’s pointer dead dead bites extreme number, continuously 30 minutes even one millimeter’s shaking all not allowed to appear.

Two heads’ water pressure like violently angry’s elephant crazily toward middle gap fiercely squeezes. Inspector stepping on anti-slip boots drills into iron frame below’s maintenance trench, holding a handle strong light flashlight shining middle only compared to thumb thick a little’s pressure relief port. According to Double Block and Bleed (DBB) hard indicator, small hole inside absolutely not allowed drip out one drop water spark.

“Water pressure carried past not counts finished, immediately change into 80 psi’s low pressure purity nitrogen gas toward inside blow. Water molecules volume big barely can be blocked, all-pervasive’s low pressure nitrogen gas once along sealing ring tiny scratches leaks into middle cavity body, connected at pressure relief port outside’s hose inserted at water tank inside, one second not reach just will gurgling toward outside pop white bubbles.”

Bumping into giving high risk natural gas pipeline supplying goods’ order, buyer will take acceptance standard one breath pull high to DIB-1 Double Isolation and Bleed‘s abnormal level. Two sides’ two pieces big steel balls cannot again do one-way defense. Every one piece ball’s inside outside two circles metal sealing seats, respectively independently carry double-way reverse pouring’s high pressure gas flow. Inspector takes iron lump left right two sides’ flange pipeline ports all open wide ventilate.

Only left middle that 0.5 cubic meters’ narrow empty cavity, toward inside reversely inject up to 100 bar’s high pressure nitrogen gas. Ball body outer side that circle bright dazzling’s metal face on all smeared full one layer thick thick’s transparent soap water. Two inspectors wearing goggles one person dead dead staring one head, eyes one blink not blink ground look full 15 minutes.

As long as pops out one compared to sesame seed big’s gas bubble, heavy reaching 3 tons’ iron lump on the spot is knocked on unqualified’s red seal. 20 degrees Celsius room temperature under’s routine inspection merely is an opening. Sent to Canada Alberta province extremely cold oilfield’s pipe fittings, all must be stuffed into two floors high’s liquid nitrogen freezing cabin inside suffer one round big sin.

Freezing cabin inside’s thermometer screen one way madly drops to minus 46 degrees Celsius, thick reaching 80 millimeters’ cast steel outer shell on forms full one layer two centimeters thick’s white frost. Hydraulic mechanical arm grabbing up above’s actuator connecting rod, at ice hole inside forcefully simulates workers at on-site’s switch actions. Full load pressure’s freezing state under back and forth twists whole 200 times.

• Valve stem on wrapped’s graphite packing cannot shatter drop down half a bit black dregs
• Computer force measuring gauge displayed’s switch torque must not exceed room temperature under’s 1.5 times
• Internal nickel base alloy spring’s encountering cold shrinking amount controlled at 0.2 millimeters inside
• Connecting two halves valve body’s high strength bolts at cold shrinking stress under not allowed appear yielding pulling long
• Sealing face still must carry 2250 psi highest water pressure’s reverse mad reverse pouring

Extremely cold barrier suffered past, immediately moved to fireproof testing field put one handful big fire fiercely burn. Oil refinery occurs pipeline catching fire time, valve became protecting life’s last one path solid blocking fire wall. Operator takes steel wire rope takes equipment tied on open-air testing frame on, below surrounding ignited whole twelve pieces industrial level gas big blowtorches.

1000 degrees Celsius’ deep blue flame takes hundreds kilograms heavy’s metal shell forcefully burned till all red. According to API 6FA fireproof specification, at fierce fire inside fully dry burned full 30 minutes not stopping. Inside that circle PTFE plastic sealing ring early just melted into a puddle popping black smoke’s smelly water.

Hiding at backward’s metal to metal backup fireproof sealing ridge, this time hard carried pipeline cavity inside fluid’s violent impact. Testing period toward outside leaked out’s water amount, calculated down every inch pipe diameter every minute absolutely cannot exceed 400 milliliters passing line. Big fire just extinguished, fire fighting small team’s thick water gun facing burned red’s iron block fiercely sprays ice cold cold water.

Tons of cold water poured up, huge temperature difference aroused sky full white color high temperature water vapor, outer shell emits crackling’s metal screaming sound. Iron wall bearing extremely violent’s thermal expansion cold contraction tearing pulling force, one strip hair thread wide’s crack all not allowed to pop out. Whole set sixty more items non-human tests endured finish, quality inspection supervisor just will pick up hammer knock down API qualified steel seal.

chemical media handling

Double Isolation

Chemical plant’s thick big carbon steel pipe inside flowing 98% concentration‘s fuming sulfuric acid or extremely easily volatilized’s liquid ammonia. These high risk liquids with per second 3 meters’ speed at pipe inside surge, pipe wall all year round bearing 2.5 MPa’s huge inner pressure. Ordinary single layer metal baffle plate supports not past half a month, surface is by acid liquid scoured out 0.5 millimeters deep’s groove.

Factory at one heavy reaching 300 kilograms’ overall forged iron lump inside, side by side stuffed in two pieces diameter 250 millimeters’ solid stainless steel round balls. Boiling hot’s acid liquid solidly hits on first piece ball body on. Ball body back behind padded one circle special plastic ring, is by several tons heavy’s water pressure dead dead topped against, like a wall same forcefully cut off surging’s toxic water.

• 12 roots alloy springs dead dead top against
• Hard carry 99% destructive impact
• 260 degrees high temperature under not deforming

Passed through three ten thousands times above’s forced switch friction, first piece iron ball surface hard to avoid will be by pipe inside’s gravel scraped. Every hour has about 15 milliliters’ strong acid along hair thread same’s scratch seeps past. Two pieces metal balls middle artificially dug out one capacity 2.2 liters’ closed empty cavity.

Originally up to 100 bar’s terrifying fluid impact force is by first piece ball body completely unloaded away, middle empty cavity inside’s pressure dropped to 0.1 bar below. Summer ground surface temperature reaches 65 degrees, metal pipeline is roasted till burning hot. Empty cavity inside remaining’s several milliliters waste acid liquid receives heat violently expands. Environment temperature every rises 5 degrees, closed space inside’s pressure will soar to 15 MPa.

Super high pressure extremely easily takes iron flange middle’s graphite washer squeezed shattered. Outer shell middle opened one inner diameter 15 millimeters’ small hole, connecting one set sensitive’s mechanical spring device. Empty cavity inside’s pressure exceeds pipeline design upper limit’s 1.3 times, spring is topped open. Trace amount’s toxic gas along small hole all runs to factory building outside’s waste gas tower inside washed clean.

• Automatically pop open pressure relief small valve
• 0.2 seconds empty super pressure toxic gas
• Guide flow into dedicated waste liquid tank

Second piece stainless steel ball hiding at this exhaust empty cavity’s backward, comfortably staying at zero pressure’s quiet environment inside. It even one thread one hair’s strong acid scouring all feels not to, round smooth’s spherical face like mirror same intact without damage. Front’s first piece ball body replacing it blocked down all’s violent wind rainstorm, it quietly pasting sealing ring, taking remaining’s several drops toxic liquid thoroughly sealed dead.

Downstream pipeline arrived at must replace aging parts’ time, three names maintenance workers holding 1.2 meters long’s big wrench exactly desperately disassembling M36 specification’s heavy type bolts. Worker took off anti-toxic mask big mouth breathing, body distance pipe inside highly toxic’s hydrofluoric acid not reach 80 centimeters. Has behind this piece entirely without damage’s ball body dead dead blocking, pipe inside loading one hundred tons’ toxic liquid also comes not over.

Traditional single piece metal ball valve at highly toxic environment under’s physical damage rate is about thousandths five. Two pieces ball valves front back queuing standing together, superimposing middle’s waste liquid pumping empty design, pipeline leaking toxic gas’s probability dropped to two ten thousand five thousands one. Large scale refining chemical device continuous machine starting operating 36 months absolutely not stop vehicle, worker possessed extremely spacious’s maintenance time difference.

Leading shift shift leader every day holding flashlight patrolling pipeline, dead dead staring middle sewage port’s that piece pressure gauge. Dial face reading toward up jumped 0.1 scales, indicating front that piece ball leaking water became more. Worker holding carrying pressure injecting grease gun, spends 15 minutes time hits in half kilogram heavy’s special fluorine element sealing mud, rushing at toxic water rushing toward second path defense line before takes tiny cracks dead dead blocked up.

Two functions

Factory deep night’s pipe gallery big frame on, leaving ground 25 meters’ maintenance platform on standing two names wearing air respirators’ operators. Facing front is one strip marking has bright yellow color ring’s 10 inches caliber pipeline, inside sealed holding concentration up to 99.5%’s liquid chlorine. Two sides flange plates are by 8 roots thick strong’s metal screw rods dead dead hinged tight. Workers holding a handle long reaching 60 centimeters’ F type explosion-proof wrench, preparing twist open middle that root outer diameter merely 20 millimeters’ sewage fine pipe.

Past’s 24 hours inside, roughly has 150 milliliters’ highly toxic chlorine liquid permeated past first layer special alloy spherical face. Worker using force presses down wrench, fine pipe on’s needle type small valve is counterclockwise twisted open two circles. Cavity room inside holding’s 2.5 MPa high pressure liquid chlorine, instantly found one coin size’s venting outlet.

One burst carrying nose-piercing smell’s white mist along stainless steel corrugated hose, with per second 8 meters’ flow speed rushes toward 150 meters outside’s alkali liquid washing tower. Not reach 45 seconds, closed cavity room inside’s gauge pressure reading from 2.5 MPa rapidly dropped to 0.01 MPa’s micro positive pressure state. Remaining’s extremely small amount free chlorine gas molecules, is by following injected’s 0.6 MPa dry high purity nitrogen gas thoroughly replaced flushed.

• Use 15 cubic meters per hour’s nitrogen gas continuously blowing sweeping 10 minutes
• Hand-held portable gas detector pasting small hole measuring taking numbers
• Screen displays chlorine gas concentration lower than 0.5ppm’s safety red line

Workers take thick big’s sewage hose one handful pull down, confirming cavity room internal clean clean. Two pieces blocking road’s steel balls between became a not having any toxic gas remaining’s vacuum buffer zone. Downstream exactly disassembling large scale reaction kettle cover plate’s maintenance shift group, hand inside carrying dozens catties heavy’s steel iron accessories, nostril inside smelling not to one thread one hair’s nose-piercing abnormal smell.

Fine pipe terminal end is temporarily added installed one piece dial face diameter 150 millimeters’ mechanical pointer pressure gauge. Workers did not immediately move fire cutting pipeline, but at platform on quietly stood whole 15 minutes. Eyes dead dead staring glass gauge cover below’s that root black color metal fine needle. Pipe network control room’s big screen on, upstream main pipeline still bearing 4.0 MPa’s strong conveying pressure.

Gauge needle like rusted same stopped at number 0 scale line on absolutely still, explaining upstream’s first piece stainless steel big ball intact without damage. Gauge needle occurs even if one millimeter’s mechanical deflection, climbs to 0.05 MPa‘s scale, leading shift leader’s explosion-proof walkie-talkie just will hurriedly sound up. Weak’s pressure change accurately exposed upstream PTFE sealing washer on’s one strip extremely fine crack.

Medium with per minute 50 drops’ speed quietly penetrates that layer damaged plastic washer, along metal ball body edge flows into middle cavity room. Discover gauge needle toward up tilts up, platform on’s personnel immediately put down hand inside’s all angle grinders. Worker picks up communication equipment calls 500 meters outside’s central dispatch room, requests whole line stop vehicle reduce pressure.

Day shift inspector morning 8 o’clock punctually steps over leaving ground 50 centimeters’ explosion-proof threshold. Pipe wall outside wrapping thick reaching 80 millimeters’ aluminum silicate insulation cotton. Worker’s thick canvas gloves touch toward two pieces metal big balls middle’s that three-way metal joint. Joint on self carries one thread spacing 1.5 millimeters’ testing fast socket.

Worker takes carrying along’s mechanical gauge head using force presses in, hears crisp’s metal shrapnel buckle sound. Pipe network inside running temperature up to 180 degrees’ liquid benzene, dial face outer shell is burned till unable to use hand touch.

Equipment monitoring part	On-site physical performance	Instrument pressure data	State judging result
Middle fine pipe exhaust port	Continuously sprays out high pressure nose-piercing white mist	Dial face maintains at 0.5 MPa above	Upstream first path defense line scrapped
Dial face black color indicating needle	15 minutes inside slowly rises one grid	Reaches 0.1 MPa and continuously climbs	Plastic sealing ring scraped seeping leaking
Hand-held testing probe	Screen displays number 0.0 not alarmed	Zero gauge pressure without any mechanical fluctuation	Mechanical physical isolation 100% intact

Factory full load producing, background electronic system automatically scans every one piece patrol photo’s pixel difference. Discovers pointer exists 0.02 MPa’s physical displacement, one piece carrying red frame’s maintenance sheet is printed out.

Early exposed tiny wearing parts, protected whole strip annual output value 3 hundred million yuan’s chemical production line. One small can weight merely has 800 grams’ special repairing resin, along backup injecting grease hole is by high pressure pump forcefully pressed into scratched’s spherical face gap inside. Worker spent 20 minutes blocked up leak point, exempted taking 15 tons heavy’s valve body overall disassembling’s huge engineering.

Resisting corrosion

Factory area northeast corner’s pipe gallery inside walking high concentration’s hot hydrochloric acid, liquid temperature all year round maintains at 120 degrees Celsius. Liquid inside filled with extremely active’s chlorine ions, like countless handles naked eye cannot see’s micro saw blades. Ordinary’s 304 stainless steel steel plate put in, not reach 48 hours just will be gnawed eaten out densely packed’s holes. Ordinary iron valve contacts this kind medium, 3 millimeters thick’s inner wall at half a month inside just will fester perforate.

In order to deal with extremely strong corrosiveness, double ball valve’s outer shell changed on heavy reaching 450 kilograms’ Hastelloy alloy (Hastelloy C-276) solid forged steel block. Steelmaking workers at special metal inside mixed in up to 16%’s molybdenum element and tungsten element. These two kinds trace metals at encountering acid’s instant, will at surface condense out one layer thickness merely being 10 nanometers’ dense protective film.

Even if pipe inside pressure soars to 10 MPa, this layer naked eye unable to perceive’s chemical film also firmly adheres on metal surface, forcefully carrying high purity hydrochloric acid tens of thousands times’ violent scouring.

Metallurgical industry uses Pitting Resistance Equivalent Number (PREN) to measure one piece metal anti-rusting’s ability. Life inside common’s 316 stainless steel’s numerical value barely reaches 25. Double valve selected’s super duplex steel (SAF 2507) at manufacturing time passed through 1050 degrees’ high temperature solid solution treatment, anti-corrosion numerical value soared to 42 above.

Bumping into 98%’s boiling fuming sulfuric acid, even highest level’s alloy also supports not live long years accumulated months’ soaking. Workers take double ball valve internal all can contact to acid liquid’s surface, all pasted on one layer thick reaching 5 millimeters’ special meltable PTFE (PFA) plastic. 200 degrees’ high temperature under, high pressure injection molding machine takes liquid plastic forcefully squeezes into metal inner wall’s capillary holes inside.

• At 220 degrees Celsius’ special made oven inside continuously baking 72 hours
• Plastic and bottom layer metal’s pulling peeling strength up to 8 MPa
• Surface’s mechanical smoothness did to Ra 0.1 micron level
• Boiling hot acid liquid flows past just like water drops rolling past lotus leaf same without any remaining

Ordinary’s nitrile rubber at hydrogen fluoride gas inside soaks 30 minutes just will expand into one puddle rotten mud. Here changed on manufacturing cost extremely expensive’s perfluoroether rubber (Kalrez) O type sealing ring. One strip diameter 200 millimeters’ black rubber ring, can at 300 degrees’ high temperature acid mist inside maintain 5 years above’s initial elasticity.

First piece covered full plastic’s round ball topping at most front, alone ate down pipeline inside 99%’s chemical corrosion damage. Tens of thousands times gravity switch after, front section plastic face is by hard’s solid catalyst particles scratched out 0.2 millimeters deep’s cut. Extremely small amount’s acidic steam along crack drills past, drops into two pieces ball bodies middle that volume being 3.5 liters’ emptying metal cavity room.

Cavity room bottom’s sewage pipe port installed has extremely sensitive’s titanium alloy float. One small mouthful acid mist just condensed into 5 milliliters’ liquid drops, sewage fine pipe just is by float automatically topped open, waste liquid along corrugated pipe flows into outer side’s collecting bucket.

Forced emptying mechanism takes extremely small amount’s corrosive substances rapidly pumped away, hiding at backward’s second piece backup round ball touching not to one drop acid liquid. Back section ball body’s surface even one strip compared to hair thread still fine’s corrosion spot all find not out. Pipeline terminal end those hundreds of thousands one unit’s precision probes, exempted being by acid liquid long term soaking burned down’s ending.

Long reaching dozens kilometers’ open air pipe network sun shining rain pouring, different materials’ metal touching together extremely easily produces galvanic cell destroying reaction. Double valve external’s fasteners all changed into B8M level’s heavy type stainless steel bolts, thread surface smeared thickness being 0.05 millimeters’ molybdenum disulfide anti-rust grease. 16 roots thick strong’s threaded studs at coastal salt mist environment inside exposed whole three years, maintenance worker takes ordinary wrench one twists just open.

Flaw detector personnel hand inside holding 20 thousand volts’ high pressure electric spark testing instrument, pasting valve inner wall’s plastic coating slowly sweeping past. Even if coating on exists one diameter 0.01 millimeters’ naked eye leaked coating micro hole, instrument just will crackling sound and pulls out blue color’s electric arc. Leaving factory before 100%’s strong electric spark flaw detection sweep tail, sealed dead strong acid seeping into metal base material’s last one strip extremely tiny channel.

high-integrity isolation

Working principle

Worker using force rotates external’s reduction box hand wheel. Huge’s gear group takes person’s hand strength amplified 100 times, produces 850 Newton meters’ rotation force. Internal first piece solid steel ball clockwise rotates 90 degrees, takes not opened hole’s smooth that face turns over. Pipeline inside 200 bar (about 2900 psi)’s high pressure natural gas just like a wall violent’s water wall, ruthlessly hits on steel ball surface on.

Ball body bottom’s metal roller bearing steadily carried quite a few hundreds tons’ physical impact force. High pressure gas along hair thread like’s tiny metal gap, toward inside drilled to sealing ring’s back face. Gas’s thrust adding on mechanical spring original’s elastic force, takes one circle polyetheretherketone (PEEK) material’s plastic washer dead dead presses on steel ball on. Local pressure instantly soars to 30 MPa, even extremely tiny’s methane molecules all are blocked at outside.

Resisting pipeline inside extremely harsh’s industrial fluid, sealing components’ selecting material near harsh:

• Fluorine rubber: carries live 180°C, soaked at crude oil inside long years not deforming.
• Polyetheretherketone: tops against 260°C high temperature, endures live long time’s strong friction.
• Tungsten carbide coating: hardness reaches HRC 72, not afraid carrying sand gas crazily polishing.
• Pure graphite ring: specially for carrying 600°C above’s extreme fierce fire baking prepared.

Ten thousandths one’s trace amount gas extremely luckily squeezed past first path defense line, they immediately drop into two pieces giant steel balls middle’s closed empty cavity inside. Empty cavity inside’s pressure gauge pointer from 0 starts slowly toward up climbs. High pressure gas runs to second piece steel ball’s back face applies reverse thrust. Pressure more big, toward inside pushing squeezing’s strength just more ruthless, forcefully takes second piece sealing ring toward inside pushes, dead dead hugging tight second piece steel ball.

Maintenance master holding dedicated long handle wrench walks to huge’s steel iron equipment beside. Twists open two pieces steel balls right middle one root 1/2 inches thick’s 316 stainless steel exhaust small pipe. Middle empty cavity inside accumulated’s that a little bit dangerous gas, along this root pipe all safely discharges toward chemical plant high altitude burning’s torch. Empty cavity dial face on’s pointer instantly drops back 0 scale.

Every one unit heavy equipment leaving factory before, must experience extremely rough’s physical extreme testing:

• High pressure gas tight: hit in nominal pressure 1.1 times’ gas dead dead holding live 15 minutes.
• Helium gas capturing: takes mass spectrometer grasps leaking out amount smaller than 10’s negative 6 power millibar liters’ tiny leaking gas.
• Extremely cold pulling: whole machine soaked into minus 196°C liquid nitrogen pool measuring calculating hand wheel rotating’s strength.
• Internal violently supporting: toward shell inside pouring water adding pressure to 1.5 times observing thick big’s steel rod will not will break.

Rod bottom is cut out one bottom big up small’s inverted cone shape rough step. Pipe inside’s fluid pressure more big, bottom that piece PTFE plastic anti-dropping washer just is toward up topped till more flat. Assembly worker at steel rod and ball body between, stuffed in one root not reach fingernail cover size’s stainless steel small spring. Dry gas high speed friction produced’s ten thousands volts static electricity, all along spring guides into thick heavy’s metal shell discharges into underground.

Chemical plant suddenly occurs big fire, surrounding air temperature at three five minutes inside straightly forces 1000°C. Internal originally tightly fitting’s plastic soft washer is instantly roasted melted into ash. Losing plastic soft supporting’s giant steel ball is by high pressure gas toward front fiercely pushed several millimeters. Smooth’s metal ball body directly hits on backward in advance left out’s that one circle metal edge. 100 bar’s thrust takes surface roughness only has Ra 0.1 microns‘ metal face hard touching hard bites together, blocked live fire ground inside possible occurring’s severe leakage.

Cutting these dozens tons heavy’s industrial metal lumps, machine tool’s dimension requirement extremely harsh:

• Steel ball roundness: high low undulating error is forcefully suppressed at 0.005 millimeters inside.
• Metal shell thickness: specially extra add 3 millimeters metal used to resist hydrogen sulfide long years corrosion.
• Bolt pulling force: use large scale hydraulic wrench hard drag to yield strength’s 50%.

One unit 36 inches’ heavy pipeline equipment, put on ground scale on exceeds 15 tons heavy. External hard’s shell uses ASTM A350 LF2 specification’s low temperature carbon steel whole block at fire stove inside forged out. Dozens roots thumb thick’s high strength alloy double head bolts, take left right two halves pig iron lumps dead dead locked together. Internal erupts again fierce’s liquid water hammer physical impact, external thick heavy’s cast steel shell even one thread tremble all feels not to.

Industrial application scenes

Sea surface wind waves slapping high towering’s steel structure pillars, platform distance nearest’s land exceeds 200 kilometers. North Sea oilfield’s drilling platform on, worker activity deck’s area compared to half a football field still wants small. Space extremely restricted, intricate’s pipeline only can seeing gap inserting needle ground stacked together. Extracted out’s high pressure crude oil mixing extremely possessing corrosiveness’s sea water and mud sand, internal pressure all year round tops at shocking’s 10,000 psi (about 690 bar).

Equipment maintenance period arrived, three names wearing anti-flash burning suits’ electric welders need to cut open one section damaged’s 12 inches oil pipe. Pipeline inside leaking out not reach hundreds milliliters’ combustible hydrocarbons, electric welding gun spraying out’s 2000°C high temperature electric arc instantly just will take whole platform blow up into fire ball.

“At four sides surrounding sea’s iron lump on moving fire cutting, our body behind fundamentally not has retreating road. Pipeline isolation blocks not live high pressure gas, all people even jumping sea’s opportunity all not have.”

Two units heavy’s valves combining one section 3 meters long’s short pipe, occupied nearly 5 meters’ physical space, total weight exceeds 8 tons. Hoisting this set old components must mobilize platform on biggest’s 50 tons level cantilever crane.

Transforming plan takes huge’s three pieces set changed into one long merely 1.8 meters’ integrated double ball valve. Heavy type forged steel shell internal stuffed in two sets independent’s sealing pieces, whole machine weight forcefully chopped off nearly 40%. Two pieces flange connecting faces disappeared, bolt loosening leading to high pressure salt mist seeping leaking’s probability straight line slides down.

Responding extreme working conditions, marine equipment’s anti-corrosion and bearing pressure parameters have extremely rigid’s standard:

• Spraying thickness reaches 400 microns’ epoxy zinc-rich primer resists high concentration salt mist.
• Fastening bolts change into super duplex stainless steel (UNS S32750) material.
• Internal flange gasket adopts Inconel 625 alloy resisting hydrogen sulfide cracking.
• Valve body outer shell pre-leaves out 5 millimeters thickness’s pig iron used to cope with sea water long years corrosion.

Line of sight turns back land, occupying land area up to thousands acres’ large scale oil refinery exactly executing three years one time’s whole factory big maintenance. High towering’s catalytic cracking device stops operating, beside’s ethylene cracking furnace still exactly with 800°C’s temperature full load burning. Dense like spider web’s pipeline inside flowing purity up to 99%‘s liquid benzene and highly toxic hydrogen sulfide.

Five names cleaning workers carrying heavy’s oxygen bottles, along narrow’s iron climbing ladder drills into diameter 4 meters’ huge reaction kettle. Internal space extremely stifling, dark inside only can rely on safety helmet on’s explosion-proof headlamp illuminate. Connecting this iron tank’s feeding pipeline diameter reaches 24 inches, normal times every hour surges in thousands tons’ flammable chemical raw materials.

Reactor internal belongs to absolute’s restricted space, any toxic gas’s concentration reading exceeds millionths ten (10 ppm), detector just will crazily alarm.

Huge’s double ball valve dead dead stuck at feeding pipeline and reaction tank middle. Upstream steel ball blocks 1.5 MPa’s highly toxic liquid. Middle cavity room bottom’s discharging liquid port connecting one root 2 inches thick’s hose, pipe other one head connecting chemical plant’s waste liquid recycling pool. Front’s steel ball is by impurities scratched leaks past several drops toxic liquid, all along hose flow away. Cleaning worker head top’s portable gas detector screen on, hydrogen sulfide concentration reading steadily stops at 0.0 ppm.

North winter heating period, crossing three provinces’ natural gas main line every day conveys exceeding 40 million cubic meters’ fuel. Pipeline inside maintaining 100 bar’s high pressure, gas flow speed approaching per second 15 meters. Construction team at not having stopping gas breaking flow’s circumstance under, at main line on executing carrying pressure opening hole operation, giving newly built’s city distributing gas station connecting natural gas.

Main line stopping operating one day, downstream three hundred communities’ radiator pieces several hours inside just will ice cold. Construction personnel at main line on welded one huge’s three-way pipe fitting, hung on heavy reaching 5 tons’ carrying pressure opening hole machine. Cutting knife head at 100 bar pressure’s impact under, forcefully takes thickness 18 millimeters’ X80 level pipeline steel pipe wall drills through.

Pipe network connection and high pressure cleaning operation tolerates not half a bit sand:

• Main line pipe cleaning machine with per hour 10 kilometers’ speed pushes away remaining accumulated water.
• Bypass branch line pipe diameter shrinks to original’s one third go rein live violent gas flow.
• Ultrasonic flaw detector back and forth scans weld seam capturing even if 0.2 millimeters’ internal sand hole.
• Receiving cylinder terminal end dead dead tops against every square centimeter 100 kilograms’ huge impact.

Huge’s knife head carrying cut down’s round shape metal block slowly retreats back outer shell. Bottom’s double ball valve relying on externally connected’s hydraulic pump station provides power, two sets heavy type pistons push out 70 MPa‘s strong hydraulic strength, forcefully take two pieces diameter half meter’s giant steel balls push to closing position.

Operator walks to connection point, twists open two pieces valve seats middle’s sewage small iron valve. Accompanying ear-piercing’s mechanical whistling sound, several cubic meters’ high pressure methane along empty venting riser pipe rushes toward dozens meters high’s mid-air. Dial face pointer smashes back zero point, backward long reaching two kilometers’ newly built pipeline is completely hit through. Whole set actions doing finish, main line inside surging’s natural gas even one second all not have stagnated.