Tungsten Carbide vs Stellite vs Ni-Based Alloy for Metal Seated Ball Valves | Which One Cuts Cost Without Losing Performance

WC hardness HRC65–75, wear resistance best, suitable for containing >25% particle medium, lifespan improves 3 times but cost high about 20%;

Stellite hardness HRC40–50, temperature resistance 800℃, anti-cavitation, cost-performance ratio medium;

Ni-based alloy hardness HRC30–40, corrosion resistance excellent, cost low about 15%.

Strong abrasion choose WC, comprehensive working condition choose Stellite, corrosion priority choose Ni-based.

material cost

Stellite: cost extremely high

Last year a certain week, unit price within a few days shot up 15%, one ton could sell to nearly 40,000 US dollars. Stellite powder inside has a large half all being cobalt element, mass proportion high reaches 50% to 65%. Globally produced cobalt raw ore has 60% more coming from Congo (Kinshasa), remote mining areas plus a few multinational mining giants limitedly releasing goods, lifted the price high unreachable.

New energy vehicle factory’s purchasers hold big handfuls banknotes go to mining area snatching goods to make batteries. Making industrial valves’ factories go to buy Stellite powder, got quotation sheets always must on basic London cobalt price upward add 20% to 35% processing fee. One medium scale valve factory, every month buying Stellite No. 6 powder’s spending, on account book often is 2 million RMB up and down. Bumping into delivery period pressing tight, walking air freight air-shipping 100 kilograms powder, freight document’s numbers high frighteningly.

Workshop wants to Stellite surface-weld onto 316 stainless steel made sphere surface, plasma arc welding machine’s nozzle sprays out over ten thousand degrees high temperature arc light, burns melting powder. Working masters must first take tens kilograms heavy steel ball preheat to emitting dark red color, infrared temperature measuring gun shoots upward, temperature numbers all are 600°C upward. Factory building inside heating furnace no matter whether is burning natural gas or using large power electric heating wire, one day’s energy consumption bill thick one stack.

Welding gun behind connects purity reaching 99.999% high purity argon gas tank. Flowmeter’s knob twisted open, one minute runs away 15 liters argon gas. One bottle 40 liters standard large size gas cylinder, half a shift worked finished then sees bottom. Month end finance once reconciling accounts, buying shielding gas invoices big one stack.

Welded finished workpiece needs to be thrown into filled full asbestos powder iron bucket inside deadly covered holding temperature. Cooling speed slightly faster a bit, even if one minute more dropped 15°C, quiet workshop inside will hear “click” one crisp sound, surface cracks out naked eye cannot find tiny cracks. Quality inspector sprays on red penetrant coloring agent, then covers one layer white developer agent, waits 15 minutes.

Workshop old welders often complain about Stellite’s temper:

• Preheating slightly slower a bit easy to produce cracks
• Argon gas flow not stable then emits dense pores
• Arc closing technique poorer a bit edge large pieces peel off
• Single layer weld meat exceeding 3 millimeters extremely easily shells off
• Finding defects remelting repairing at most do two times

Endured past welding flaw detection torture, sent to machining workshop again is one field smashing money hard battle. Stellite surface Rockwell hardness wanders at HRC 40 to 45 up and down, hard like piece stubborn stone. Ordinary hard alloy blade just pasted up, “squeak squeak” sounding two sounds then ground flat. Worker goes to warehouse registers claiming CBN tools, one piece only has fingernail size, unit price high reaches two three hundred yuan.

Turning one caliber 6 inches ball valve sphere, programmed set cutting depth little pitifully, only 0.1 millimeters. Lathe spindle turns slowly, worked one whole morning, waste tray inside only scraped down shallow one layer metal wire. Used ruined CBN blades in machine tool underneath box inside piled into one small mountain. Counting in lathe’s machine shift depreciation fee, machining’s spending compared to making ordinary carbon steel parts more out five six times.

Tungsten Carbide: cost relatively high

Per kilogram purchase unit price perennially at 40 to 50 US dollars floats. Casually pick up several buckets 5-kilogram packed powder, bill amount can equal one small lathe’s marked price.

Worker operates overhead crane takes several hundred kilograms heavy workpiece pushes into High Velocity Oxygen Fuel (HVOF) soundproof room. Imported HVOF spraying equipment building cost exceeds 200,000 US dollars, covered with pipelines machine set occupied area fully has half basketball court big. Spray gun igniting instant, combustion chamber inside pressure soars to 120 pounds/square inch.

Tungsten carbide powder in extremely short time inside is heated to half-melted state, at per second 800 meters speed smashes toward stainless steel sphere. Speedometer’s data compared to pistol fired bullet faster out two times. Short one hour continuous spraying operation, consumed aviation kerosene invoice document amount high reaches several hundred yuan.

Giving one 10 inches ball valve sphere wear on tungsten carbide outer coat, mechanical arm driving spray gun back and forth walking tool only needs short 20 minutes. Account book on truly burning money process all hiding in behind machining workshop inside. Sprayed on tungsten carbide coating thickness deadly controlled at 0.15 to 0.3 millimeters. Hardness tester hitting upward Rockwell hardness value soared to HRC 70 above.

Machining master towards this layer thin hard shell extremely headaches. Ordinary machine tool blade just touching on coating surface, one second not reaching then chips mouth scrapped. Front treating Stellite alloy extremely easy-to-use CBN blade arriving in front completely cuts not moving. Factory spends big price buying inlaid with artificial diamond customized grinding wheel. Worker takes workpiece racking on tens of thousands yuan one special CNC grinding machine on slowly rubbing.

Grinding cutting depth deadly limited at extremely low 0.01 millimeters. Sparks splashing workshop inside, one large ball valve spherical surface processing needs to consume 20 to 40 working hours. Operator’s eyes one moment not stopping staring at cooling liquid’s flowmeter looking. Once water cuts off a few seconds, surface over thousand degrees high temperature will let coating instantly turtle-crack peel skin.

Workers take sphere and valve seat stacked putting together, smeared full imported diamond lapping paste repeatedly pair-lapping. Two heavy machines one day 24 hours continuously turning, at least grinding full three days three nights. Every separated four hours, assembler stops machine takes tens jins heavy workpiece moving down hitting on blue inspection seal oil. Holding high precision vernier caliper measures contact belt’s fitting degree.

Harsh complicated process flow birthed one big stack expensive spending details:

• Sealed HVOF soundproof room every month needs replacing building cost two thousand yuan dust filtering element
• Imported diamond grinding disc on average grinding ten spheres then will grind bald scrapped
• Holding senior certificate sprayer salary compared to ordinary welder higher out one and a half times
• Surface finish Ra0.1 harsh acceptance indicator vastly pushed high defect rate

Holding high ex-factory price document go to mine or coal chemical site settling accounts, purchasing managers pulling out money extremely refreshing. Thick big conveying pipeline inside flowing mixing hard quartz sand and coal ash high temperature black water. Flowmeter displayed flow speed reaching per second 15 meters. Ordinary 316 stainless steel ball valve installed into pipeline, less than half a month sphere surface just is washed getting thousand holes hundred sores. Whole workshop stopping machine rushing repair one time loses over millions yuan.

Changing on this tungsten carbide coating ball valve, surface hard resists hard particles crazy cutting. Continuously running two years still can achieve completely not dripping leaking. Tens of thousands yuan equipment purchasing funds allocated into 700 more days safe running cycle inside.

Ni-Based Alloy: cost-performance ratio

London Metal Exchange nickel spot listed price long-term at 16,000 to 18,000 US dollars one ton back and forth wandering. Taking it and frequently approaching forty thousand US dollars one ton cobalt put in same line chart inside looking, that line flat gentle like a pool dead water. Basic bulk commodity price stable, letting powder purchasing bottom price being deadly pressed on floor.

Valve factory purchasing department issues one hundred kilograms Ni60 alloy powder order, invoice on tax-included unit price often at 120 yuan to 150 yuan RMB one kilogram. Same one month going to buy same mesh number Stellite No. 6 powder, needs to pull out at least four hundred more yuan. Merely at warehouse material claiming window weighing checking, account book on saved down one big sum real gold white silver.

Workshop inside doing spray welding master very likes receiving nickel-based alloy production orders. Operating process no need lifting heart hanging gall, steel ball base using fire slightly roasts a bit, infrared temperature measuring gun sweeps past displaying 300°C then can work. No need taking tens jins heavy iron lump burning getting thoroughly red, natural gas valve less opening two gears, one shift saves down forty fifty yuan fuel fee.

“Welding Ni60 just like spreading pancake same smoothly, powder sprayed upward itself just melts flattening, edge fusing extremely good, arc closing that point never peels skin curls edge.”

Quality inspection department month end inventories waste warehouse’s scrapping records. Nickel-based surfacing weld parts one-time submitted inspection pass rate perennially maintains at 98.5% above. Flaw detection liquid sprayed full whole 8 inches sphere surface, waiting full twenty minutes taking strong light flashlight shining one circle, all is one piece clean cold white color, cannot find out one thread crack.

Workshop statistics actual consumables data bill extremely pretty:

• Single layer weld meat thickness can reach 4 millimeters not shelling off, process reduces one cut
• Shielding argon gas flow adjusted smaller one third, standard gas cylinder less changed one time
• Welded after thrown in air inside naturally dropping temperature not cracking, saved asbestos holding temperature bucket
• Penetrant flaw detection reagent single month consumption amount falls to original’s one third

Surfacing welded finished half product pulled into machining workshop, Rockwell hardness tester smashes down, pointer stops at HRC 55 around. Hardness value actually compared to high price bought materials even higher out one section, machine tool master working up a bit not worries. Lathe tool post on installed only is twenty thirty yuan one piece conventional YT15 hard alloy blade.

Worker takes cutting depth towards 0.3 millimeters direction pushes, cut down iron chips drop falling in machine tool chassis inside, presenting out pretty blue long strip rolls. One day continuously turning down, scrapped blades at most three four pieces, spending one hundred yuan slightly over. Workshop director month end looking material loss table on tool list can laugh out sound.

“Pair-lapping polishing most afraid surface has deep shallow not same pockmarks. Nickel material self-melting property extremely excellent, porosity extremely low, diamond lapping paste smeared upward, six hours then can grind out mirror effect.”

Drawing required Ra0.2 surface roughness, under two lapping machines day night not stopping turning very quickly reaches standard. Manual guarding at machine beside holding micrometer measuring roundness time from two days shortened to large half day. Accounting one whole 6 inches Class 300 metal hard seal ball valve general ledger, nickel-based scheme surface treatment hard cost less than 5,000 yuan.

Opening domestic large chemical plant every year thick equipment purchasing inventory, exceeding 60% process pipeline inside running is temperature less than 400°C, mixing extremely small amount sand grains room temperature or medium temperature fluid. Pipeline design pressure stuck at 2.5 megapascals to 4.0 megapascals between, wear degree far reaching not slurry pipeline that kind terrifying gnawing level.

wear and corrosion balance

Wear resistance & high hardness

Drawing requires surface hitting to HRC65. Quality inspector takes standard Rockwell indenter smashes down, hard alloy surface only leaves down one extremely shallow white point. Changing using micro Vickers equipment, testing needle tip pokes into coating, screen displays reading breaks through 1200HV. Pipeline fluid mixing 8% fine quartz sand. Whole set equipment running 120 days dismantled open, bright metal spherical surface by sand gnawed out 0.2 millimeters deep plow groove.

Factory toward steel material on sprays alloy powder, finished product thickness stuck at 0.15 to 0.3 millimeters between. High pressure airflow takes powder accelerates to per second 800 meters bumping toward valve seat base. Taking bearing coating sample block fixed on pulling machine toward two sides pulling, reading stays at 70 megapascals, thin attached layer echoing sound peels off.

Coating too thin, encountering fluid internal big particles fiercely impacting, bottom ordinary steel material like dough downwards caves in. R&D room uses pin-on-disk machine doing friction consumption comparison. Hanging on 50 Newtons heavy weight, grinding disk every minute fixed turning 200 circles. Pure dry grinding 30 minutes, taking high magnification microscope measuring scratch width.

• Nickel-based pure powder: scratch width 1.8 millimeters
• Mixed in 20% chromium carbide: scratch narrowed down to 0.9 millimeters
• Big particle cobalt-based powder: scratch left 0.6 millimeters
• Pure tungsten steel hard phase: scratch only has 0.15 millimeters

Boiler discharged steam temperature climbs up to 480℃, metal micro state occurs changing. Bonding tungsten steel particles metal cobalt becomes soft, originally 1200HV extremely high value landslides falling to 800HV below. High temperature fluid bringing pressure fiercely rushing, in blocks hard particles following pipeline dropping off losing.

Room temperature under measuring pure cobalt-based alloy, instrument reading only has HRC42. Taking test sample block thrown into muffle furnace heating to 650℃ thoroughly roasting through. Taking long handle tongs clamping out taking advantage thoroughly red state hitting hardness, value stably maintains at HRC38. High temperature under not softening high red hardness extremely fits refinery working condition. Pipeline inside full is bringing extremely strong cutting force catalyst powder, sealing surface as before biting tightly.

Slurry pipeline mixing impurities extremely possess destructive power. River sand Mohs hardness is 7, aluminum oxide particles approach 9. Conventional 17-4PH stainless steel treated finished hardness HRC44, suffering aluminum oxide washing just like using wood cutting ice block. Fluid internal carrying different sizes stone blocks, will on metal surface leave down completely different destruction marks.

• 50 micrometers fly ash: taking spherical surface more grinding more bright
• 200 micrometers stone sand: like iron plow digging out clear deep groove
• 1 millimeter ore slag: in blocks smashing off surface metal skin
• 300℃ high temperature coking: toward steel material internal squeezing out pits

Changing using large plasma equipment barely taking thickness piled to 1 millimeter. Thickness increasing letting coating internal holds full stress, residual tensile stress instrument measures out 150 megapascals. Pipeline connecting high pressure liquid, sphere receiving force turning squeezing several times, thick coating on spot exploding collapsing.

Changing using ten thousand degrees high temperature plasma arc to burn. Special alloy powder and base steel material together melt into iron water, melt pool downwards digs away 1.5 millimeters deep. Two metals thoroughly turning into one body. Taking sample taking to pulling machine on violently pulling, bonding surface’s tensile strength soars to 350 megapascals, with stainless steel base material equal solid.

Cutting open fusion welded metal block measuring profile parameters. Outermost one layer anti-wear hard skin measures out HRC55, middle transition zone drops to HRC40, bottommost stainless steel only has HRC20. Suffering pipeline fluid inside broken stones fiercely impacting, underneath soft meat provides sufficient buffer, outside hard shell not easy occurring shattering.

Confronting severe environment

Pipeline inside flowing 98% concentration boiling sulfuric acid. Thermometer pointer pointing at 120℃, ordinary carbon steel pipe wall soaking in inside, one week’s corrosion thinning amount reaches 3 millimeters. Metal surface like throwing into water inside effervescent tablet same crazily emitting out hydrogen bubbles.

Conventional tungsten carbide coating encountering bringing acidity liquid will rapidly collapse. Fluid pH value dropping breaking 3.5, as coating skeleton metal cobalt by acid liquid quietly hollowed out. Hard dense spherical surface in 15 days inside covered full sponge-like tiny holes, sealed cabin room pressure from 10 megapascals rapidly dropping zero.

Nickel-based alloy Hastelloy C276 contains 16% molybdenum element. Chemical plant pipeline internal containing 10000 ppm chloride ions, ordinary 304 stainless steel putting in inside 3 days being bitten through.

Material anti-pitting capability has one special test value called PREN. 316L stainless steel PREN value stuck at 25 around. Encountering coastal high concentration salt water washing completely not enough looking. Laboratory takes Inconel 625 nickel-based alloy taking doing comparison, its PREN value high reaches 45.

Material name	Boiling sulfuric acid annual corrosion rate	5% hydrochloric acid annual corrosion rate	Chloride ion tolerance upper limit
316L stainless steel	Greater than 5.0 millimeters	Greater than 2.0 millimeters	1000 ppm
Tungsten carbide (cobalt bonded)	Greater than 3.0 millimeters	Greater than 1.5 millimeters	Not applicable extremely poor
Stellite No. 6	0.8 millimeters	0.5 millimeters	5000 ppm
Hastelloy C276	0.05 millimeters	0.01 millimeters	Over 50000 ppm

Natural gas extraction site wellhead pressure climbs up to 20 megapascals. Just pumped out original gas inside mixing 15% hydrogen sulfide. High pressure under hydrogen sulfide molecules nowhere not entering, drill into metal crystal lattice internal taking hydrogen atoms releasing out. High hardness steel material surface having no omen cracking open one 0.5 millimeters wide big mouth.

According to NACE MR0175 petroleum industry anti-corrosion standard, anti-hydrogen sulfide forcibly requires controlling hardness. Workshop takes Inconel 718 alloy hardness suppressing at HRC35 to HRC40 between. Retaining metal material toughness, hydrogen atoms at grain boundary place wandering unable to break metal atom arrangement micro grid.

Sulfuric acid plant waste liquid pipeline flow speed determined as per second 15 meters. 20% concentration dilute sulfuric acid mixing finely broken gypsum crystal blocks rushing toward sealing surface. Pure titanium material in static acid liquid inside can perfectly place 1 year, fluid moving up surface titanium oxide thin film immediately by gypsum cut broken, 24 hours inside corroding through 3 millimeters thick pipe wall.

Refinery catalytic device pipeline temperature perennially staying at 850℃. Extreme high temperature letting originally stable oxygen molecules become frantic. Ordinary stainless steel with blazing hot oxygen gas contacting, surface growing out 0.5 millimeters thick black oxide skin. Equipment opening closing running, thick black skin large area dropping off stuck dead in transmission shaft gap inside.

Stellite alloy inside stuffed into 28% chromium element. Encountering 800℃ above high temperature baking, surface rapidly precipitates out one layer chromium oxide protecting layer. Taking it putting into 900℃ muffle furnace inside dry burning 100 hours taking out weighing, per square meter surface area only lost less than 2 grams metal.

Extreme hot after often accompanying extreme cold testing violent devastation.

• 3 minutes inside taking part from 400℃ hot furnace rapidly thrown into -40℃ ice water.
• Toward testing cabin infusing minus 196℃ liquid nitrogen continuously soaking 24 hours.
• Using 8 megapascals high pressure steam repeatedly impacting simulating factory starting machine preheating.

Base stainless steel linear expansion coefficient is 13.5, surface tungsten carbide coating only has 6.0. Taking this assembled well metal block heated to 500℃, outer layer deadly pulling inner layer, microscope under floating appearing 0.05 millimeters wide net-like micro cracks.

Parts back side narrow gap width not sufficient 0.1 millimeters. Fluid drilling in coming not out, local area pH value in 6 hours inside plummets to 1.5. Standard anti-corrosion steel material at this dead corner position soaking 48 hours, giving birth to a puddle red brown iron rust mud. Workshop changing using full nickel-based base going on machine tool cutting, taking processing tolerance shrinking to 0.02 millimeters, thoroughly erasing potion liquid retention space.

Extremely excellent red hardness

Refinery ethylene cracking furnace pipeline outer wall burning getting thoroughly red, infrared temperature measuring gun hitting on pipe wall jumping out 750℃ dazzling number. Ordinary martensitic stainless steel placing high temperature under roasting, physical state just like one piece softening toffee candy. Room temperature under measured 600 megapascals yield strength, stepping into high temperature cabin plummeting to even 50 megapascals all not enough. Pipeline internal pressing 15 megapascals high pressure gas flow fiercely pushing squeezing, valve body metal parts occurring severe twisting deforming.

Workshop taking one piece Stellite No. 6 special cobalt-based sample block throwing into 800℃ heating furnace, fully burning 4 hours until thoroughly transparent glowing. Fitter taking long handle tongs clamping out taking advantage hot pushing on testing table, dial pointer deadly nailed at HRC38. Taking it out throwing into 20℃ cold water tank inside fast cooling, again going on machine measuring hardness, reading stably stopping at HRC42.

Factory inside bringing apprentices old technician mouth ear mutually passing one iron law: “Exceeding 600 degrees pipeline, don’t care room temperature data how pretty, all must give cobalt-based alloy yielding position.”

Two pure metal spheres at 550℃ dry hot sealed cabin room inside mutually heavy pressure rubbing, surface not having any lubricating grease protecting. 316 stainless steel surface friction coefficient instantly crazy soaring to 0.8 above, metal surface layer occurring extremely tragic tearing micro welding. Stopping machine dismantling open cabin door checking, sphere surface covered full 0.5 millimeters deep rough pockmark pits.

Cobalt-based special alloy inside mixing in 6% tungsten element and approaching 30% chromium powder. Tiny tungsten atoms firmly locking dead metal crystal lattice internal sliding surface, 600℃ high temperature under friction coefficient forcefully suppressed at 0.35 around. Simulating pipeline opening closing action continuously rubbing 10000 times, sealing surface washing clean as before smooth, micrometer measuring out less than 0.02 millimeters extremely slight wear.

Room temperature state under tungsten steel surface extremely anti-manufacturing (highly durable), environment temperature crossing 500℃ threshold defense line fully collapsing. Bonding tungsten steel particles metal phase at high temperature roasting under becoming soft loosening, overall volume occurring 0.1% tiny expansion. Per second 30 meters flow speed high temperature coal ash facing face sweeping passing, tungsten steel hard layer like loose sand same large area continuous pieces peeling off, pipeline two hours inside losing all cutting off capability.

• 500℃ metal creeping: part dimensions receiving heat stretched long 0.2 millimeters, thoroughly sticking dead transmission shaft
• 650℃ oxidation peeling skin: surface layer growing out 0.3 millimeters thick black gray oxide, in blocks stripping dropping off
• 800℃ grain boundary melting: internal low melting point impurities turning into liquid state, receiving force instant occurring breaking

National level testing center report 12th page attaching one photo: “Continuous 96 hours 700℃ hot state opening closing circulation testing, spherical surface not seeing scratch, nitrogen gas leaking amount 0.08 drops/minute.”

Coal chemical gasification furnace discharging slag mouth inner wall temperature in short 20 seconds inside from 200℃ wildly rising to 650℃. Accompanying huge temperature difference rushing facing coming, per second running 20 meters super high flow speed high temperature coal slag broken pieces smashing toward pipe wall. Cobalt-based alloy internal carbide net-like structure in violent thermal expansion cold shrinking inside maintaining extremely high stability, continuously carrying staying 2000 times above ice fire alternating, X-ray flaw detection not seeing one thread thermal fatigue crack.

Production line surfacing welding special thick skin, base steel material must putting into furnace inside preheating to 450℃ constant temperature. Plasma welding gun spraying out arc, 2 millimeters thick pure cobalt welding wire turning into iron water evenly paving opening. Operation finishing immediately throwing into asbestos powder holding temperature box, strictly according to per hour dropping 30℃ speed extreme fast dropping temperature, little by little releasing off internal accumulating 200 megapascals residual tensile stress.

Large refinery catalytic cracking device regenerator, every day forcibly transporting 3000 tons extremely boiling hot catalyst powder. Room temperature testing high reaching HRC60 carburizing hardened steel installed upward surviving not reaching three months, spherical surface by living gnawed away 2 millimeters deep. Changing installing red hardness extremely excellent cobalt-based forging part, large machine set continuously 24 hours running full 36 months then pulling down pipeline doing major repair.

lifecycle value

Purchasing price low

4 inches caliber nickel-based coating ball valve marked price 4500 yuan. Adopting supersonic spraying process tungsten carbide material ball valve unit price high reaching 12800 yuan. Two purchasing lists putting together, differing full 8300 yuan. Buying one tungsten carbide valve money can buy returning three ordinary nickel-based valves.

Newly built 150 meters long lime water conveying pipeline installed upward this cheap nickel-based valve. Pipe inside lime water concentration reaching 20%. Fluid inside mixing large amount seeing not sharp small particles. These particles at per second 2.5 meters speed continuously washing internal metal parts.

Nickel-based coating surface hardness at HRC45 up and down. Short three days after, originally smooth metal surface being washed out 0.05 millimeters deep tiny scratch marks. Breaking damage point once appearing, dropping off speed then will multiply increasing. Water flow following cracks toward inside drilling, half a month then taking scratch marks washing wider 40%.

Originally tightly fitting valve seat starting toward outside leaking water. Sealing testing instrument displaying data falling to not qualified interval. Site working workers finding opening closing becoming especially wasting effort. They only can taking pneumatic device input pressure adjusting higher, forcibly taking pipeline holding back closing dead.

Usually only needing 60 Newton meters strength then can twisting moving valve, now needing 140 Newton meters. Matching pushing air cylinder long time over load working. Beside solenoid valve coil temperature very fast scalding hand, temperature measuring gun hitting upward displaying 85 degrees Celsius.

Machine repairing master notebook on recording down one pile troublesome daily spending:

• Every week two trips going to site twisting tight flange bolts
• Every month dismantling changing one time PTFE sealing gasket
• Air cylinder parts single time scrapping losing 320 yuan
• Every time dispatching two old fitters working full 4 hours

Saved down that 8300 yuan price difference at 45th day thoroughly turned into empty head check (bounced check). Whole metal sealing surface completely wearing through, cutting off fluid function scrapping. Pipeline inside lime water losing control, reverse pouring into beside clear water storing tank. Whole annual producing 50,000 tons production flow line being forced pulling down electric switch stopping work.

Washing that being polluted big tank using off 8 tons pure water. Four workers holding high pressure water gun continuously washing 12 hours. Machine stopping turning half day less producing 150 tons finished products. Flipping looking this batch goods market quotation unit price is 2200 yuan one ton. One time expectation outside stopping work letting factory instantly less earning 330,000 yuan.

Merely for saving down buying valve 4500 yuan, behind troublesome spending like rolling snowball same rising to large tens of thousands. Warehouse only can continuing spending money buying exactly same cheap goods returning substituting. One year coming down this kind nickel-based valve full changing 8 pieces. These 12 months inside, pipeline leaking off industrial raw materials occupying total amount 1.2%.

Factory building floor trench every day in vain flowing away 300 liters bringing chemical potion dirty water. This kind dirty water once discharging into municipal pipe network then will provoke upward big trouble. Environment Protection Bureau very fast sending coming water quality exceeding standard testing list. Together sending coming still has one piece 50000 yuan fine notice letter.

Workshop supervisor enduring not every day repairing equipment, changing upward one batch unit price 7500 yuan Stellite alloy valves. Containing cobalt metal at 350 degrees Celsius high temperature under as before can maintain HRC42 hardness. Pipeline at same washing environment under continuous running recording pulling long to 180 days. Half year not dismantling not repairing letting machine repairing class less adding 6 times night shift.

Most expensive tungsten carbide material surface hardness breaking through HV1050. Per second 2.5 meters material flow speed hitting on upward even white marks all leaving not down. Recording notebook on writing full one whole year 365 days working time length. Thickness measuring instrument dotting at coating surface, reading out thickness loss number merely only has 0.015 millimeters.

Beside that leaking amount testing instrument on pointer steadily stopping at 0.3 milliliters/minute position. Account book on one big pile usually seeing not miscellaneous fees spending being thoroughly erased off:

• Warehouse spare parts piling area vacating out 85%
• Crane entering factory moving fee single time saving down 1200 yuan
• Waste liquid environmental treatment fee every bucket less spending 800 yuan
• Automatic flow line defect rate dropping 0.5%

Taking calculating accounts time span pulling long to five years full 60 months. Cheap nickel-based valves total buying returning 40 pieces. Hardware purchasing invoices accumulating to 180,000 yuan. Matching dismantling installing buying graphite gaskets, anti-rust screws and lubricating oil again spending off fifteen thousand yuan. Looking like cheap hardware parts taking total spending pushing to ceiling.

Marked price 12800 yuan tungsten carbide valve at these five years inside even pipeline all not coming down past. Only at third year returning factory doing one time surface polishing grinding. Master manual lapping sphere receiving 1500 yuan working hours fee. This expensive equipment five years total spending deadly stuck at 14300 yuan this number on.

Five years time settling accounts comparing, two account books on numbers difference exceeding 180,000. Thickness only having mere 0.3 millimeters super hard metal coating playing decisive role. This layer not catching eyes gray hard shell firmly locking down fluid. It forcefully intercepting down every second 50 grams material in vain losing.

Anti-wear & anti-corrosion

Chemical plant liquid conveying pipeline installing full temperature high reaching 80 degrees Celsius, pH value only being 2.5 dilute sulfuric acid. Pure acid liquid day night eroding metal internal parts. Nickel-based alloy at this specific acid washing pool inside displaying out extremely good account book return.

Metal internal chromium element encountering acid liquid rapidly starting reaction, at surface generating one layer thickness 3 micrometers dense oxidation film. Thin film deadly blocking hydrogen ions continuing toward deep place permeating. One caliber 6 inches nickel-based hard seal ball valve at pure dilute sulfuric acid inside continuously soaking 48 months. Dismantling open re-inspecting not at metal surface finding even 0.1 millimeters corrosion pits.

As long as liquid inside clean clean not having sand, nickel-based coating then can steadily safely working. Beside another pipe connecting coal chemical black water pipeline. Fluid inside mixing going in 15% mass fraction coal slag particles. Originally having surface balance being instantly breaking broken.

HRC 45 hardness nickel-based oxidation film being sharp coal slag cutting broken. Acid liquid following 0.05 millimeters tiny cracking mouth drilling into metal deep place. Acid liquid corroding overlapping particles scraping, two streams destructive power back and forth pulling. Only using 14 days, valve core sphere surface just being gnawed out one diameter 12 millimeters deep pit.

Maintenance class from warehouse transferring coming Stellite alloy valve substituting. Material inside mixing in extremely high cobalt element, room temperature hardness measuring as HRC 52. Changing to 450 degrees Celsius, 12 MPa pressure superheated steam pipeline inside, high cobalt material welcoming extremely excellent working state. Steam inside bringing boiler inner wall dropping off iron rust skin one way wildly running.

Superheated steam flow speed approaching per second 60 meters. Stellite coating at high temperature roasting under not will becoming soft, temperature measuring gun hitting upward as before maintaining HRC 45 value. Small block iron rust impacting at surface, only leaving down one path naked eye barely seeing clear white mark. Machine running recording notebook on free repairing time breaking through 300 days.

Cobalt-based alloy facing medium strength scraping having ample room to play. Pipe cutting into polycrystalline silicon plant silicon powder conveying line, situation occurring losing control. Pipe inside blowing sending quartz powder hardness reaching Mohs 7 level. Cutting off valve every day enduring 40 times high frequency opening closing friction.

Stellite coating at 90th day losing coming down. Valve seat sealing ring being living grinding off one circle thickness reaching 1.5 millimeters metal chips. Leak measuring instrument probe putting at flange interface place, reading out every minute 85 milliliters severe leaking amount.

Tungsten carbide powder being supersonic flame at 2 Mach speed fiercely smashing at metal base on. Forming dense coating hardness tester hitting out HV 1050 limit value. Mohs 7 level silicon powder bumping upward, like taking plastic spoon to scrape bulletproof glass. Continuously scraping two years having no traces.

Site three recording books writing down different working conditions real consumption spending:

• Pure strong acid pipeline matching nickel-based coating, 48 months not wearing through holes, saving down repairing fee 1200 yuan
• High temperature bringing slag steam using Stellite, 10 months blocking 60 meters/second washing, exempting 3 times major repairing
• High hardness coarse particles handing to tungsten carbide, 90 days wearing only 0.02 millimeters, intercepting down whole line stopping machine bad luck

Three kinds bulletproof vests facing two different cutting tools hacking, presenting out extremely clear resisting bottom line. Laboratory testing data completely restoring pipeline internal day after day slaughtering results.

Protecting coating material	Anti-pure acid alkali corrosion years	Coping solid particles hardness upper limit	Sealing surface generating 0.1 millimeters wear consuming time
Nickel-based alloy (Ni-Based)	48 months no breaking damage	Mohs 3 level below	14 days (pipeline containing 15% solid content)
Stellite (Stellite 6)	36 months no surface dropping off	Mohs 5 level below	300 days (per second 60 meters flow speed)
Tungsten carbide (HVOF WC)	12 months (encountering strong alkali binder losing)	Mohs 8 level below	Over 800 days (daily 40 times high frequency friction)

Report on numbers taking each’s short boards lighting clearly cleanly. Nickel-based facing pure acid pure alkali having no fearing color, bumping bringing sand stone fluid immediately breaking defense. Stellite at 450 degrees extremely high temperature under same style carrying general hardness impurities scraping. Tungsten carbide surface hard like diamond, all relying on inside metal cobalt doing binder.

Taking hard incomparable tungsten carbide soaking into concentration 30% sodium hydroxide strong alkali pool inside. Playing bonding role metal cobalt will be little by little pumping dry hollowing out. Losing grasping hands tungsten carbide particles following water flow in pieces dropping off. High reaching twelve thousand yuan heavy armor being pure chemical reagent relaxing melting solving.