Lecture on n.a.c.e Mr-0175-2000

Z:\Dat\Training\Experienced\JBTermination

N.A.C.E FOR SULFIDE ENVIRONMENT

N.A.C.E MR-0175-2000

LECTURE

ON



Corrosion

This is defined as chemical or electrochemical reaction between a material,usually a metal and its environment that produces a deterioration of the materialand its properties.



Crevices corrosion : Localized corrosion of a metal surface at ,or immediately adjacent to, an area that is shielded from full exposure to the environment because of close proximity between the metal and the surface of another material

Pitting: Forming small sharp cavities in surface due to localized corrosion, wear or any other mechanically assisted degradation.Inter-granular corrosion: Corrosion occurring preferentially at grain boundaries, usually with slight or negligible attack on adjacent grain.Selective leaching: Corrosion in which one element is preferentially removed from an alloy ,leaving a residue (often porous) of the elements that are more resistant to the particular environment (decarburization, decobaltification, denickelification , dezincification and graphitic corrosion)

.Erosion corrosion: A conjoint action involving corrosion & erosion in the presence of a moving corrosive fluid, leading to accelerated loss of material.

Stress corrosion: Preferential attack of areas under stress in a corrosive environment, where such an environment alone could not have caused corrosion.

.Hydrogen damage: In the presence of hydrogen environment in certain material hydrogen induced embrittlement, cracking & blistering occurs this is called hydrogen damage.

Uniform attack: In this form of corrosion the corrosion proceeds at the same rate over the metal surface.



The Basics of Sulfide Stress Cracking

Sulfide -stress cracking is basically a hydrogen-embrittlement phenomenon .Atomic hydrogen enters the steel to cause cracking. The hydrogen is generated on the surface of the steel because of a corrosion reaction. Iron reacts with h2s to form iron sulfide and hydrogen .This hydrogen is generated in atomic form on the steel surface ,where it can either combine to form molecular hydrogen and leave the surface as bubbles or diffuse into steel .This latter process may result in hydrogen embrittlement .Hydrogen sulfide prevents hydrogen recombination & thus promote entry of atomic hydrogen into steel .It is important to note that water must be present for this mechanism to occur ;without it SSC will not be observed ,because the ionization of the hydrogen sulfide is required.

SSC develops in aqueous solutions as corrosion takes place on the surface of a material. Hydrogen ions are a product of many corrosion processes. These ions pick up electrons from the base material producing hydrogen atoms. At that point, two hydrogen atoms may combine to form a hydrogen molecule. Most molecules will eventually collects, for hydrogen bubbles and float away harmlessly. However, some percentage of the hydrogen atoms will diffuse into the base metal and embrittle the crystalline structure. When a certain critical concentration of hydrogen is reached and combined with a tensile stress exceeding a threshold level, SSC will occur. H2S does not actively participate in the SSC reaction; however, sulfides act to promote the entry of the hydrogen atoms into the base material.In many instances, particularly among carbon and low alloy steels, the cracking will initiate and propagate along the grain boundaries. This is called intergranular stress cracking. In other alloy systems or under certain specific conditions, the cracking will propagate through the grains. This is called transgranular stress corrosion cracking.



PARAMETERS AFFECTING THE RATE OF SSC

— HYDROGEN SULFIDE CONCENTRATION

— Ph OF THE SOLUTION

— TEMPERATURE OF THE SOLUTION

— STRENGTH OF THE MATERIAL

—COLD WORK ON THE MATERIAL

—STRESS ON THE MATERIAL



History of NACE

NACE STANDS FOR NATIONAL ASSOCIATION OF CORROSION ENGINEERS

•1959 T-1B COMMITTEE BY WESTERN CANADA ENGINEERS

•1963 ISSUE OF SPECIFICATION 1B163 “ RECOMMENDATION OF MATERIAL

FOR SOUR SERVICE”

•1965 NATION WIDE COMMITTEE FORMED T-1F-1

•1966 T-1F-1 RELEASED SPECIFICATION 1F166

•1975 T-1F-1 RELEASED SPECIFICATION MR0175

•NOW ANNUALLY IT IS RELEASED BY T-1 COMMITTEE WHICH CONSTITUTE OF 500 ENGINEERS

•LATEST REVISION IS MR0175-2000



•INTENDED FOR OILFIELD EQUIPMENT

•NOW APPLIED IN OTHER PLACES LIKE LNG PLAN,REFINERIES ETC

•ONLY SULFIDE STRESS CRACKING IS ADDRESSED

•NOT A DESIGN STANDARD–ONLY A GUIDELINE FOR MATERIAL SELECTION & PROCESSING METHOD–DECISION ON THE USER–HOWEVER IN SOME PART OF WORLD MANDATORY AS PER LEGISLATION



•ADDRESSES:

– HEAT TREATMENT OF MATERIALS– ALLOWABLE HARDNESS LEVELS– MECHANICAL WORK HARDENING– POST WELD HEAT TREATMENT– FABRICATION TECHNIQUES– BOLTING MATERIALS– PLATING & COATINGS



APPLICABILITY OF MR175-2000

•MR0175 shall be applicable only when the partial pressure of HYDROGEN SULFIDE in a wet gas phase of a gas , gas condensate ,or crude oil system is equal to or exceeds 0.05 psia

•It is not applicable for following condition

1. When the total pressure is less than 65psia

2. When the total pressure is less than 265psia ,the max. gas/oil ratio(scf/bbl)is 5,000

or less, and the H2S content is less than 15mol% and the H2S partial vapour pressure

content is less than 10psia.



EXAMPLEGiven below an example taken from GNFC gasifier project.Composition in KG-MOL/HR

COMPONENT FLUID RATE IN KG-MOL/HRCO 1075.92H2 1076.502CO2 106.706H2O 2406.187C1 10.058AR 8.621N2 5.559H2S 3.778COS 0.094NH3 3.262TOTAL 4696.687

PARTIAL PRESSURE OFA GAS IN AN MIXTURE IS CALCULATED AS FOLLOWMOLAR WT. OF THE GAS/TOTAL MOLAR WT) X TOTAL PRESSURE

i.e P.P OF H2S =(3.778/4696.687) * 81.978 KG/CM2 = 0.006594284 KG/CM2 = 0.941125 PSIAIn the above example the partial pressure of H2S is greater than 0.05 psia so for this service NACE is applicable



NACE REQUIREMENT FOR VARIOUS MATERIAL

The requirement of NACE MR0175 is described in two basic form of materials1.FERROUS METAL2.NON-FERROUS METALThe evaluation of this materials for pipelines & pressure vessel steel has to be performed as per procedure given in NACE standard TM0284 & testing of metals for resistance to sulfide stress cracking at ambient temperatures in NACE standard TM0177



FERROUS METAL

The material having iron as principal component.This is having below listed categories

•CARBON & LOW-ALLOY STEEL

•FREE MACHINING STEEL

•CAST IRON

•AUSTENITIC STAINLESS STEEL

•FERRITIC STAINLESS STEEL

•MARTENSITIC STAINLESS STEEL

•PRECIPITATION HARDENING STAINLESS STEEL

•DUPLEX STAINLESS STEEL



CARBON STEEL & LOW ALLOY STEEL

Carbon steel •CARBON CONTENT LESS THAN 1%( LOW CARBON STEEL LESS THAN 0.3%,MEDIUM CARBON STEEL 0.3 TO 0.6 %,HIGH CARBON STEEL 0.6 TO 1%)

Low Alloy steel •TOTAL ALLOYING ELEMENT CONTENT GREATER THAN 2.07%(NICKEL,CHROMIUM,MOLYBDENUM)•TOTAL CHROMIUM LESS THAN10%

REQUIREMENT OF NACE•HARDNESS LESS THAN 22HRC•NICKEL PERCENTAGE LESS THAN1%•POST WELD & COLD HEATTREATMENT TO BE DONE•MATERIALS–SA216 GRADE WCB & WCC–SA105–SA352 GRADES LCB &LCCAs per KRUPP UHDE standard ES-AD 3 MAX cold shaping of the metal allowable is 5%



CAST IRON

• CAST FERROUS ALLOYS •THE CARBON CONTENT EXCEED THE SOLUBILITY OF CARBON IN AUSTENITE AT THE EUSTECTIC TEMPERATURE

•CAST IRON CONTAINS AT LEAST 2% CARBON PLUS SILICON AND SULFUR AS MINIMUM.

Gray, austenitic and white cast irons cannot be used for any pressure retaining parts, due to low ductility. Ferritic ductile iron to ASTM A395 is acceptable when permitted by ANSI, API or other industry standards.



FREE MACHINING STEEL

•ALLOYING ELEMENT LIKE SULFUR,SELENIUM OR LEAD ADDED TO IMPROVE MACHINING CHARACTERISTIC

AS PER NACE THIS MATERIAL IS NOT ALLOWED



STAINLESS STEEL

•STEEL CONTAINING MORE THAN 10% CHROMIUM

•FIVE CATEGORIES

– MARTENSITIC STAINLESS STEEL

–FERRITIC STAINLESS STEEL

–AUSTENITIC STAINLESS STEEL

–PRECIPITATION HARDENING STAINLESS STEEL

–DUPLEX STAINLESS STEEL



304 (“18-8”)Fe-18 to 20 Cr.8 to 10 Ni

Add CR and Ni for strength and oxidation resistance

309, 310, 314, 330

Add Ni for corrosion resistance in high temperature environment

Ni-Cr-Fe Alloys

Add Mo for pitting resistance

316

Add more Mo for pitting resistance

317

Superferritic stainless steels

Add Cr.

430

No Ni, ferritic

Add Nb + Ta to reduce sensitization

347

Add Ti to reduce sensitization321

Lower C to reduce sensitization

316l

317l

304l

Add Ni, Mo, N for corrosion resistance

Superaustenitic stainless steel

Add S or Se for machinability

Increase Cr, lower Ni for higher strength

Add Cu, Ti, AI, lower Ni for precipitation hardening

Add Mn and N, lower Ni for higher strength

No Ni addition, lower Cr, martensitic

303, 303 Se

Duplex stainless steel

Precipitation hardening stainless steels

201, 202

403, 410, 420



MARTENSITIC STAINLESS STEEL

•MARTENSITE MICRO STRUCTURE

•STRUCTURE FORMED DUE TO FAST COOLING

•CHROMIUM 10.5 TO 18%, CARBON GREATER THAN 1.2%•NACE REQUIREMENT– HARDNESS MAX 22HRC•HEAT TREATMENT PROCEDURE–NORMALISE OR AUSTENITIZE & QUENCH–TEMPERING TWICE AT 620 DEG. CEL.AND THEN COOLING TO AMBIENT TEMP.–AFTER COLD WORK STRESS RELIEVED AT 620 DEG CEL

• COMMON MATERIAL APPROVED BY NACE AND ARE COMMONLY USED ARE–UNS S41000 (410 stainless steel SST) (FORGE)–A217 GR CA 15 (CASTINGS)–A486 CL CA6NM(CASTINGS)



FERRITIC STAINLESS STEEL

•HAVING FERRITIC MICROSTRUCTURE

•COMPOSITION MAINLY CHROMIUM 11 TO 30%

•NOT USUALY USED FOR INSTRUMENTATION ONLY FOR PIPES & AUTOMOTIVE

PARTS

•SUPERALLOYED FERRITE HAVING GOOD RESSTANCE AGAINST SSC



AUSTENITIC STAINLESS STEEL

•AUSTENITE MICRO STRUCTURE(FACE CENTRE CRYSTALLINE PHASE)

•COMPOSITION CHROMIUM 16 TO 26% ,NICKEL LESS THAN 35%, MANGENESE

LESS THAN 15%

•NACE REQUIREMENT–MAX HARDNESS 22HRC–GOOD RESISTANCE TO SSC IN ANNEALED CONDITION–COMMONLY USED MATERIAL IN CAST FORM & WROUGHT FORM ARE 302,304,304L,305,308,309,310,316,316,316L,317,321,347 AND UNSN08020(ALLOY 20-UPTO 32HRC)



PRECIPITATION -HARDENING STAINLESS STEEL

• CHROMIUM NICKEL GRADE STEEL HARDENED BY AGEING (AUSTENITIC (A-286), SEMI AUSTENITIC(17-7PH), MARTENSITIC(17-4PH))

•HIGH YIELD STRENGTH,GOOD DUCTILITY & TOUGHNESS

•NACE REQUIREMENT– 17-4PH CAN BE USED IN WROUGHT FORM(S17400) ALSO IN CAST FORM (CB7Cu-1) FOR MAX 33HRC–S66268(A286 GRADE 660) FOR MAX 35HRC–S20910 (NITRONIC 50) FOR MAX 35 HRC COMMONLY USED FOR SHAFTS,STEM &PINS



DUPLEX STEEL

•CONSIST OF TWO MICROSTRUCTURES(AUSTENITIC / FERRITIC)

•TYPICAL COMPOSITION CARBON LESS THAN

0.3%,MOLYBDENUM,NITROGEN,TUNGESTEN,COPPER,CHROMIUM(20 TO 30%) &

NICKEL (5 TO 8%)

•HIGH STRENGTH,DUCTILITY,GOOD RESISTANCE TO CHLORIDE SSC & PITTING

•GENERALLY NOT USED IN INSTRUMENT APPLICATION USED MOSTLY FOR VESSEL

MANUFACTURING DUE TO HIGH STRENGTH THIN WALL THICKNESS REQUIRED



FERRITIC MARTENSITIC PRECIPITATIONHARDENING

AUSTENITE DUPLEX(AUSTENITIC/FERRITIC)(WROUGHTCONDITION ONLY)

AISI AISI ASTM AISI UNS-S31260405 410 A453 GR 660 302 UNS-S31803430 501 A638 GR 660 304 UNS-S32404

304L UNS-S32550305 UNS-S32760308 UNS-S39274309 UNS-S39277310316316L317321

347

ASTM ASTM UNS S17400 ASTM CAST DUPLEXA268 A217GRCA15 UNS S45000 A182 (AUSTENTIC/FERRITIC

)TP405,TP430

A268 GR TP410 UNS S66286 A193 STAINLESS STEEL

TPXM27,TPXM33

A743 GR CA 15M GR B8R,B8RA,B8 Z6 CNDU 28.08 M

A487 CI CA 15M B8M,B8MA NF A320-55 FRENCHA487 CI CA6NM A194 NATIONAL STANDARDUNS S42400 GR 8R,8RA,8A,8MA UNS J93380

A320 UNS J93404GR B8,B8MA351GR CF3,CF8,CF3MCF8M,CF7MA743GR CN7MA744GR CN7MB463B473



NONFERROUS ALLOYS

• The nickel-base alloys are acceptable to a maximum hardness level of 35 HRC. All have excellent resistance to SSC. • Commonly used acceptable materials of nickel copper alloys MONEL 400,MONEL R405 M35-1 and M35-2 (cast alloy 400) and and the precipitation hardening alloy MONEL K500. • The nickel chromium alloys include alloys INCONEL 600 and INCONEL X750). • The acceptable nickel-chromium-molybdenum alloys include alloys INCONEL625 , HASTEALLOY C276 and HASTEALLOYC ( cast alloy C). The precipitation hardening grade INCONEL 718 is also acceptable to 40 HRC. • Where high strength levels are required along with good machinability, valve manufacturer uses N05500, N07718, N07750 or N07725 (alloy 725). They can be drilled or turned, then age hardened. • Several cobalt base materials are acceptable, including R30035 (alloy MP35N), R30003 (Elgiloy) and R30605 (Haynes 25” or L605).•Aluminum base and copper alloys may be used for sour service, but the user is cautioned that severe corrosion attack may occur on these materials. They are seldom used in direct contact with H2S.•Several wrought titanium grades are now included in MR0175. The only common industrial alloy is wrought R50400 (grade 2). Cast titanium is not included in MR0175.



NICKEL-COPPER ALLOYS.UNSN05500 – MONEL K500 OR K MONEL.UNSN04400 – MONEL 400 OR ALLOY 400.UNSN04405 - MONEL R405 R 405 NICKEL-IRON-CHROMIUM ALLOYS.UNSN08800- INCOLOY 800 OR ALLOY 800

NICKEL-CHROMIUM ALLOYS.UNS N06600 –INCONEL 600.UNS N07750 – INCONEL X750 OR ALLOY X750

NICKEL –CHROMIUM –MOLYBDENUM ALLOYS.UNS N06625 – INCONEL 625.UNS N10002 – HASTELLOY C.UNS N10276 – HASTELLOY C276.UNS N07718 – INCONEL 718 OR ALLOY 718.UNS N06002 - HASTELLOY X.UNS N06975 – HASTELLOY G-3.UNS N07031 – PYROMET 31



COBALT-NICKEL-CHROMIUM-MOLYBDENUM ALLOYS.UNS R30035 – MP35N.UNS R03004 - HAVAR.UNS R03003 – ELGILOY

COBALT-NICKEL-CHROMIUM –TUNGSTEN ALLOYS.UNS R30605 – HAYNES ALLOY 25

COBALT-NICKEL-CHROMIUM-MOLYBDENUM-TUNGSTEN ALLOYS UNS R30260 – DURATHERM 2602



INSTRUMENTATION & CONTROL DEVICE

•For instrumentation & control device component directly exposed to sour environments shall be of materials as described above. However AISI Type SS316 Stainless steel compression fittings and instrument tubing can be used though it does not satisfy the hardness criteria as explained why explaining the austenitic stainless steel.



BOLTING

• The most commonly used fasteners for “exposed” applications are ASTM A193 grade B7M bolts and A194 grade 2M nuts. They are tempered and hardness tested versions of the B7 and 2H grades. HRC 22 is the maximum allowable hardness.

•Many consultant (E.I.L) use only B7M bolting for bonnet, packing box, and flange joints. This reduces the likelihood of SSC if a leak develops and goes undetected or unrepaired for an extended time.

•Since B7M has lower strength using of this material requires pressure vessel de-rating. Some vendors offers special S17400 double H1150 bolting at the full B7 rating to overcome the de-rating problem.

•ENC(electrolyses nickel) coating is acceptable on pressure retaining and non pressure retaining fasteners.

•As per EIL standard only below listed materials to be used for studs & nuts .STUDS: ASTM A193 GR B7M/ASTM A320 GR L7M.NUTS: ASTM A194 GR 2HM/ ASTM A194 GR 7M



COATINGS

Coatings, plating and overlays may be used provided the base metal is in a condition, which is acceptable per MR0175. The coatings may not be used to protect a base material, which is susceptible to SSC. Coatings commonly used in sour service are chromium plating, electroless nickel (ENC) and nitriding. Overlays and castings commonly used include CoCr-A (Stellite or carbide alloys are acceptable in the cast, cemented or thermally sprayed conditions such as welding, silver brazing or spray metallizing systems. Ceramic coatings such as plasma sprayed chromium oxide are also acceptable. However during this above thermal procedure the substrate should not get heated up beyond critical temp. and stress gets created. Valve manufacturer often uses ENC as a wear resistant coating. As required by MR0175, it is applied only to acceptable base metals. ENC has excellent corrosion resistance in sour, salt containing environments. TABLE FOR ALLOWABLE MATERIALS FOR COATING & OVERLAYS1 Co-Cr-W ALLOYS AS IN A.W.S(American Welding Society) A5.13-802 Ni-Cr-B ALLOYS AS IN A.W.S(American Welding Society) A5.13-803 Tungsten Carbide Alloys4. CERAMICS5 Ni-B ALLOYS



SPRINGS

Springs in compliance with NACE represent a difficult problem. To function properly, springs must have very high strength (hardness) levels. Normal steel and stainless steel springs would be very susceptible to SSC and fail to meet MR0175.

In general, very soft, low strength materials must be used. Of course, these materials produce poor springs. The two exceptions allowed are the cobalt based alloys, such as R30003 , which may be cold worked and hardened to a maximum hardness of 60 HRC and alloy N07750 which is permitted to 50 HRC.



HEAT TREATMENTSStress Relieving

•Mainly intended for relieving locked in stresses in weld joints & cold working stresses in base metal by heating the metal below critical temperature holding the constant temp. and then cooling slowly.No change in microstructure.•Many people have the misunderstanding that stress relieving following machining is required by MR0175. Provided good machining practices are followed using sharp tools and proper lubrication, the amount of cold work produced is negligible. SSC resistance will not be affected.MR0175 actually permits the cold rolling of threads, provided the component will meet the heat treat conditions and hardness requirements specified for the given parent material. Cold deformation processes such as burnishing are also acceptable. Below table gives the details of temperature at which the metal has to be heated as per MR0175.(BASED ON THICKNESSES ASME SECTION VIII HAS ALSO TO BE REFFERED ) Sno. MATERIAL TEMPERATURE DEG CEN.1 CARBON STEEL 595 (min)2 MARTENSITIC STEEL 620 (MIN)3 LOW CARBON MARTENSIC STEEL 620 (MIN)3 LOW CARBON MARTENSIC STEEL 620 (MIN)



ANNEALING

Annealing is a generic term denoting a treatment that consists of heating to and holding at a suitable to a suitable temperature followed by cooling at an appropriate rate,primarily for softening of metallic materials.As the hardness of steel increases during cold working, ductility decreases and additional cold reduction becomes so difficult that the material must be annealed to restore its ductility.In this procedure the heating is above the critical temperature and due to this micro structure changes occur.



NORMALISING

Heating a ferrous alloy to a suitable temperature above the transformation range and then cooling in air to a temperature substantially below transformation range. With this process basically the steel microstructure is getting uniformly distributed and the mechanical properties are changing (e.g. carbon steel normalization leads to higher strength )



SOLUTION ANNEALING

For stainless steel when heated chromium- carbide gets precipitated at the boundary of the grains which in turns make the steel ineffective against corrosive attack. Above heat treatment is done at temp. at1150 deg cel. And the temp. is brought below 300 deg cel. within 3minutes by putting it into chloride free water.This process disintegrates chromium carbide and chromium goes back into the steel.This heat treatment is mandatory for SS if any hot operation is done on the steel.



CODES AND STANDARDS BESIDES MR-0175 TO BE USED FOR H2S SERVICE

Some related standards are given below which are related to MR0175.

API 6A “Specification for valve and wellhead equipment”

API 6D “Specification for pipeline valve,steel gate ,plugs,ball &check valve ”This standard requires manufacturers of API equipment to produce and maintain a document control system must

API 941 “Steel for Hydrogen service at elevated temperatures and pressures in petroleum & petrochemical plants”This standard gives the selection of material based on partial pressure of hydrogen & temperature and also explain the mechanism of hydrogen induced corrosion

ES-AD 3 “ Additional requirements for Hydrogen and/or Sour Gas Service.”



UIL EXPERIENCE WITH PREVIOUS PROJECT

a. Additional requirement asked for the PETROFAC & L&T SRU jobs1.All steel shall be killed (steel treated with strong deoxidizing agent such as silicon or aluminum in order to reduce the oxygen content to such a level that no reaction occurs between carbon and oxygen during solidification and fine grained.2.All steels shall be manufactured by either basic oxygen or electric furnace process only.

3.The following treatments during steel making are mandatory:Steel shall be made by low sulfur & low phosphorus refining process and shall be vacuum degassed while moltenSteel shall be calcium treated for inclusion morphology control to determine the effectiveness of calcium treatment “Inclusion count check “ shall be performed as per ASTM E-45Steel shall be specifically treated to control non-metallic inclusions like metallic oxide clusters, silicates & magnesium sulfide etcCarbon equivalent shall be computed as per the following formulae depending upon the carbon content..If C=<0.12 : Pcm = C + Si/30 + (Mn+Cu+Cr)/20 + Ni /60 + Mo/15 +V/10.If C> 0.12 :CE = C + Mn/6 + (Cr+Mo+V)/5 + (Ni+Cu)/15



REQUIRED CHEMICAL COMPOSITION ELEMENT PERCENTAGEC 0.23% MAXMn 1.35% MAXSi 0.10% TO 0.35%MAXP 0.02% MAXNi 0.2% MAXS 0.01 % MAXOther element AS PER ASTMPcm 0.21 MAXCE 0.4 MAX• FOR ASTM A105,A216 GR WCB,A350 GR LF2,A352 GR LCB.THIS WAS ASKED SINCE THE ABOVE COMPOSITION HAS GOOD WELDABILITY PROPERTY

• HOWEVER THE VALVE VENDORS WERE UNABLE TO DELIVER THE CASTING WITH THIS COMPOSITION INSTEAD THE VENDOR SUPPLIED A351 CF8M

• EIL HAD APPROVED SOME FOUNDRYS AND PRE -QUALIFICATION OF FOUNDRY MANDOTRY



b. UIL EXPERIENCE WITH GNFC PROJECT

In this project only two line classes had NACE requirement i.e KE61WA & KE62WAAnd the material used in this project used are listed below

FOR KE61WA (900#)/KE62WA(1500#)

SR.NO. COMPONENTS MATERIAL1. PIPE A335 GR P112. FLANGE A182 GR F113. GASKET A182 GR FR5(90-125BHN)4. VALVE BODY A217WC65. TRIM MATERIAL A182 GR F3216. NUT A193 GRB167. BOLTS A194 GR 4



CONCLUSION:-1.INSTRUMENT ENGG. SHOULD CHECK WITH PROCESS ENGG. THE APPLICABILITY OF THE STANDARD IF ANY H2S GAS IS PRESENT & ALSO CHECK IN PIPING SPECIFICATION.

2.IN G.E.S THE REQUIREMENT OF NACE SHOULD BE GIVEN.

3. MATERIAL SELECTED SHOULD BE AS PER NACE

4. WHILE CHECKING VENDOR TEST REPORT THE FINAL HARDNESS SHOULD BE CHECKED OR STRESS RELIEVING PROCEDURE IS AS PER NACE

5. DURING EVALUATION VENDOR’S MANUFACTURING PROCEDURE SHOULD BE REVIEWED.

Lecture on n.a.c.e Mr-0175-2000

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