SPC CR UR 510 3 (Important)

8/9/2019 SPC CR UR 510 3 (Important)

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Form code : MDT.GG.QUA.0505 Sh. 01/Rev. 1.94 File code: spcgnrae.dot Data file: spc_cr_ur_510_r03_e_f.doc

THE INFORMATION HEREIN AND IN THE FOLLOWING PAGES (N°35 , COVER INCLUDING) CONTAINED IS SECRET, CONFIDENTIAL AND BELONGS TO SNAMPROGETTI WHICH HAS

PROVIDED IT SOLELY FOR AN EXPRESSLY RESTRICTED PRIVATE USE. ALL PERSONS, FIRMS OR CORPORATIONS WHO RECEIVE SUCH INFORMATION FROM SNAMPROGETTI SHALL

BE DEEMED BY THEIR ACT OF RECEIVING THE SAME TO HAVE AGREED TO BE OBLIGED TO KEEP IT SECRET AND CONFIDENTIAL, TO MAKE NO DUPLICATION OR OTHER DISCLOSURE

OR USE W HATSOEVER OF ANY OR ALL SUCH INFORMATION EXCEPT SUCH RESTRICTED USE AS IS EXPRESSLY AUTHORIZED IN WRITING BY SNAMPROGETTI AND SOLELY FOR THE

SCOPE AGREED THEREIN. IN CASE OF UNDUE DISCLOSURE AND/ OR ANY FAILURE TO OBSERVE THE ABOVE PROVISIONS, THE DEFAULTING PARTY SHALL BE RESPONSIBLE FOR ANY

AND ALL DAMAGES, WITHOUT LIMITATIONS.

GENERAL SPECIFICATION

AUSTENITIC STAINLESS STEELS FOR UREA PLANT

HIGH PRESSURE SECTION

SPC.CR.UR.510

Rev.03

September 2003


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Sheet 2 (24)

Form code : MDT.GG.QUA.0515 Sh. 01/Rev. 1.94 File code: spcgnrae.dot Data file: spc_cr_ur_510_r03_e_f.docThis document is the property of Snamprogetti who will safeguard its rights according to the civil and penal provision of the law.

C O N T E N T S

1 GENERAL 4

1.1 Scope and field of application 4

1.2 Definitions 4

1.3 Abbreviations 4

1.4 Referenced Codes (always latest revision) 5

2 MATERIALS 6

2.1 General 6

2.2 316L UG stainless steel (UNS S31603) 6

2.3 25Cr-22Ni-2Mo alloy (UNS S31050) 6

3 ADDITIONAL REQUIREMENTS 7

3.1 Chemical analysis 7

3.2 Mechanical properties 8

4 TESTING AND CERTIFICATION OF MATERIAL 9

4.1 General criteria for sampling 9

4.2 Test samples and specimens 9

4.3 Microstructure examination 11

4.4 Corrosion test procedure 12

4.5 Flaw assessment test 14

Note 1: It is the sum of all defects found on 7 tube welds at all levels 14

4.6 Certification 15

5 WELDING 16

6 ADDITIONAL TESTS ON MATERIALS 23

6.1 Workshop check of ferrite 23

6.2 Non Destructive Examinations 23

7 TESTS ON PRODUCTION WELDS AND CONSUMABLES 24

7.1 General 24

7.2 Tube to tubesheet weld production mock up 24


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ATTACHMENT 1 1

ATTACHMENT 2 1

ATTACHMENT 3 1

ATTACHMENT 4 1

ATTACHMENT 5 1

ATTACHMENT 6 1

ATTACHMENT 7 1

ATTACHMENT 8 1

ATTACHMENT 9 1

ATTACHMENT 10 1


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1 GENERAL

1.1 Scope and field of application

1.1.1 This specification covers the requirements for austenitic stainless steel materials and relevantwelds in contact with the process fluid in the high pressure section of urea plants. Theserequirements shall be considered in addition to the ones of the codes and standards applicableto the product in question (equipment, piping components, plates, materials, testing, etc.). Incase of conflict with any of the above standards, this document prevails.

1.1.2 This specification takes into consideration both the 316L UG stainless steel (UNS S31603) andthe 25Cr-22Ni-2Mo type stainless alloy (UNS S31050).

1.2 Definitions

Owner: The company that has placed the order to suppliers as permitted underthe license granted by Snamprogetti.

Supplier: Before placing the order it means each of the potential supplier(s)contacted; after placing the order, it means the selected supplier(s).

Snamprogetti: Snamprogetti S.p.A., the licensor of the urea process.

316L UG: “urea grade modified” 316L type austenitic stainless steel that shall meet

all the requirements of the AISI 316L (UNS S31603) material specificationand all the additional requirements mentioned in this specification.

“sample” the piece of semifinished/ finished product (tube, plate, W.O., etc.) fromwhich the specimens to be tested are taken out

“specimen” a piece of material obtained from the sample and actually subjected to thedestructive tests described below (corrosion test, metallography, etc.).

1.3 Abbreviations

AISI American Iron and Steel InstituteASME The American Society of Mechanical EngineersASTM American Society for Testing and MaterialAWS American Welding SocietyDIN Deutsches Institut fur NürmungIIW International Institute of WeldingUG Urea Grade alloyUNS Unified Numbering SystemW.O. Weld Overlay Deposit


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1.4 Referenced Codes (always latest revision)

ASME Sect. VIII Boiler and pressure vessel code - Pressure Vessel

ASME Sect. IX Boiler and pressure vessel code - Welding and brazingqualifications

ASME Sect.V Non Destructive Examination

ASME Sect. II Parts A & D Materials

ASME Sect. II Part C Specification for welding rods, electrodes and filler metals

EN 10204 Metallic materials – Types of inspection documents

ASTM A262 Standard Practices for Detecting Susceptibility to IntergranularAttack in Austenitic Stainless Steels

ASTM E562 Standard Test Method for Determining Volume Fraction bySystematic Manual Point Count

AD MERKBLATTER Complete Technical Rules for Pressure Vessels (English Edition)


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2 MATERIALS

2.1 General

2.1.1 The list of suppliers and subvendors of plates, forgings, bars, piping and tubes for HighPressure Urea equipment and piping to be operated in contact with the urea process fluid shallbe submitted to Snamprogetti for acceptance. For filler materials the provisions of chapter 5shall be applied.

2.1.2 All semifinished products shall be supplied in the solution annealed condition. No heating over400 °C shall be allowed during machining or any other manufacturing activity, except welding.If heating above 400 °C cannot be avoided, a new solution annealing heat treatment shall then

be performed and new samples shall be taken and tested as described in chapter 4.

2.1.3 If, after solution annealing heat treatment, forgings or bars are submitted to machining andmore than 5 mm depth is removed from the side in contact with the process fluid, then a newsolution annealing heat treatment is required except for the 25Cr-22Ni-2Mo alloy provided thatthe samples taken after machining satisfy the test requirements as per chapter 4.

2.1.4 All tubes and pipes shall be seamless type. Welded fittings are allowed provided that therequirements of chapter 5 are met.

2.1.5 Cast parts and rod bars are not permitted unless approved by Snamprogetti.

2.1.6 When 316L UG material is required, the use of 25Cr-22Ni-2Mo material is allowed as an

alternative.

2.2 316L UG stainless steel (UNS S31603)

2.2.1 Stainless steel 316L UG type shall be in accordance with the ASME-(SA) specificationsapplicable to the relevant semifinished products; it shall also meet the additional requirementsdetailed in chapters 3 and 4.

2.3 25Cr-22Ni-2Mo alloy (UNS S31050)

2.3.1 Stainless steel 25Cr-22Ni-2Mo type shall be in accordance with the ASME-(SA) specificationsapplicable to the relevant semifinished products; it shall also meet the additional requirements

detailed in chapters 3 and 4.


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3 ADDITIONAL REQUIREMENTS

3.1 Chemical analysis

In the following paragraphs the chemical or additional chemical requirements for 316 UGstainless steel and 25Cr-22Ni-2Mo alloy are reported. Any deviation from these requirementsshall be subject to Snamprogetti’s acceptance.

3.1.1 316L UG stainless steel

The 316L UG stainless steel base material shall have the following additional chemicalrequirements:

C = 0.020 % max.P = 0.015 % max.S = 0.010 % max.Ni > 13 %N = 0.10 % max.

The carbon content restriction above does not apply to forgings provided no welding isperformed after the solution annealing heat treatment, not even for installation purposes.

3.1.2 25Cr-22Ni-2Mo stainless steel

The 25Cr-22Ni-2Mo stainless steel base material shall have the following chemicalcomposition:

Cr = 24 ÷ 26 % C = 0.020 % max.Ni = 21 ÷ 23.5 % P = 0.020 % max.Mo = 2 ÷ 2.6 % S = 0.010 % max.Mn = 1.5 ÷ 2.0 % Si = 0.40 % max.N = 0.10 ÷ 0.15 % B = 0.0015 % max.

3.1.3 W.O. deposit shall meet the following requirements for a depth of at least 3 mm (see

Attachment 8) from the “as welded” or machined surface:

Material type 316L UG:

C = 0.030 % max. (SAW-ESW-GTAW)C = 0.040 % max. (SMAW)Cr = 16.5 % min.Ni = 15 % min.Mo = 2.2 % min.


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Material type 25Cr-22Ni-2Mo:

C = 0.030 % max. (SAW-ESW-GTAW)C = 0.040 % max. (SMAW)Cr = 24 % min.Ni = 21 % min.Mo = 1.9 % min.and

20,1%5,0%30%

%5,1%%≤

++

++=

MnC Ni

Si MoCr

Ni

Cr

eq

eq

3.1.4 Chemical analysis at depth of 1 mm and 2 mm (see Attachment 8) shall also be performedand reported for information.

3.2 Mechanical properties

The mechanical properties of 25Cr-22Ni-2Mo stainless steel, at room temperature, shall be asfollows:

Tensile strength 580 N/mm² min.

Yield strength (0,2% offset) 270 N/mm² min.

Elongation (l=5d) 30% min.

3.2.1 Short Time Tensile Test shall be performed/ certified at the design temperature (indicated on theSnamprogetti process data sheet) for each heat of Urea Stripper heat exchanger tubes.

3.2.2 If the design is carried out in accordance with ASME code BPVC section VIII, for forgings the

code itself shall be applicable with reference to CODE CASE 2038.

3.2.3 For other requirements the relevant material/ product SA (ASME) specification shall be applied.


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4 TESTING AND CERTIFICATION OF MATERIAL

4.1 General criteria for sampling

Product Sampling for corrosion test Sampling for metallographic examination

PLATES One sample for each heat One sample for each plate

PIPING, FORGINGOne sample from each lot of no more

than 50 pieces of each heat and

same heat treatment(1)

One sample from each lot of no more

than 50 pieces of each heat and


BOLTS, NUTS,SMALL-SIZE FORGING

One sample for each heat

One sample from each lot even if of morethan 50 pieces of each heat and


for bolts, nuts, and

forgings of small size (Dia. ≤ 219,1 mm).

EXCHANGER TUBES One sample for each heatOne sample from each lot of 200 pieces

of each heat and same heat treatment(1)

NOTE (1): definition of same heat treatment:- If final heat treatment is in a batch-type furnace = in the same furnace charge- If final heat treatment is in a continuos furnace = in the same furnace at the same

temperature, time at heat, and furnace speed.

4.2 Test samples and specimens

4.2.1 Samples for corrosion tests and microstructural examination shall be taken as per the abovetable (base material) and from each weld test during the welding procedure qualification.Overheating shall be avoided when cutting the specimens (thermal-cutting is not allowed).Each sample shall be marked, by stamping, with proper identification traceability number.

4.2.2 The area of each sample shall be of 180 cm2 as a minimum (if not otherwise specified in this

document) and shall permit to take out with sufficient allowance the following specimens:

1 for check (chemical) analysis1 for corrosion test (see para. 4.4)

1 for corrosion re-testing (if required)3 for microstructure examination (see para. 4.3)1 for metallography re-testing (if required)

4.2.3 Each specimen shall include the side that will be in contact with the process fluid if known(consequently liner plates shall then be installed by exposing to the process fluid the side thathas been actually tested with positive results). Specimens for the corrosion test shall have an

area of approximately 30 – 32 cm2, weight of 40 g minimum (100 g maximum) and, when

feasible, an approximately rectangular shape with dimensions of about 50 x 25 x 5 mm.

4.2.4 In the case of plates with thickness over 7 mm, the specimen shall be reduced to 5 mm bymachining material in excess on the opposite side from that (those) in contact with the process

fluid (avoiding overheating).


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4.2.5 In the case of tubes with outside diameter less than 30 mm, the sample shall have a cylindricalshape. In the case of tubes or pipes with outside diameter ≥ 30 mm, the sample shall be takenwith length "a" approximately equal to arc "b" (see Attachment 5).

4.2.6 If the pipe or tube thickness is over 7 mm, the specimen thickness shall be reduced to 5 mmby machining material in excess on the opposite side from that (those) in contact with theprocess fluid (avoiding overheating).

4.2.7 In the case of forgings or bars, if it is not possible to take a sample with the surface to be incontact with the process fluid, the sample shall be taken from the core of the forging bar. Testspecimens shall be taken from the forging extension or by a representative specimen with thesame heat and heat treatment having maximum treated thickness size of those forgings.

4.2.8 In the case of special pieces (valves, thermocouples, fittings, instrument separators, etc.) thesupplier shall submit to Snamprogetti for acceptance an overall drawing showing the locationof the sample(s).

4.2.9 In the case of welding procedure qualification tests for SAW/ ESW/ SMAW weld overlay (seeAttachment 1) three samples shall be taken:

- sample S1 (Attachment 2) which shall include at least 2 bead overlap of adjacent beads- sample S2 (Attachment 3) which shall include stop and restart point of a bead- sample S3 (Attachment 4) which shall include beads deposited by manual welding with

SMAW and/ or GTAW on the automatic overlay, simulating repair if any.

4.2.10 The specimens obtained from each of the above samples shall be used as follows:

- specimen(s) labeled ‘A’ are to be used for metallographic analysis (one is for re-testing ifrequired)

- specimen(s) labeled ‘B’ are to be used for corrosion test

- specimen labeled ‘B1’ is to be used for corrosion re-testing if required

- specimen labeled ‘C’ is to be used for macrographic examination- specimen labeled ‘D’ is for chemical check analysis.

4.2.11 In the case of welding procedure qualification tests for additional automatic GTAW weld

overlay on liner plates or SAW/ ESW/ SMAW weld overlay, a sample of S1 type including atleast 2 bead overlap of adjacent beads (see Attachment 2) shall be taken out.

4.2.12 In the case of welding procedure qualification test for butt joints, the sample shall be as wideas the face of weld in contact with the process fluid plus 12 mm (6 mm each side) and 5 mmthick (see Attachment 6).

4.2.13 In the case of procedure qualification tests for welds between tube and tube-sheet, no. 2mock-up shall be prepared. From the first one the specimens for corrosion test andmetallographic examination shall be obtained and they shall include 3 tubes in central position.One central tube shall be used for the corrosion test, one shall be used for the metallographicexamination, one is for re-testing, if required (see Attachment 7 for details). The second mock-


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up shall be prepared following Attachment 9 and it will be subject only to the flaw assessmenttest as detailed in para 4.5.

4.2.14 The metallographic examination of the first mock-up shall be performed on the central tubeassembly previously longitudinally sectioned following 4 perpendicular directions starting fromthe second weld pass stop as follows:

a) on 4 of the 8 surfaces obtained from the sectioning a macrographic examination shall beperformed in order to determine the extension of weld fusion (which shall not exceed at anypoint 75 % of wall tube thickness), weld throat thickness (minimum weld throats of all sectionsshall be not less than the specified tube wall thickness) and penetration.

b) the 4 remaining surfaces shall be used for the microstructural examination (one surface foreach of the 3 required etchings plus one for re-testing if required).

4.2.15 The surface to be in contact with the process fluid and the opposite one if not machined shallremain in the "as received" condition.

4.2.16 The specimens shall not be subjected to any heat treatment before the test.

4.2.17 The remaining part of each sample after taking out the specimens, with the identificationnumber, shall be made available for five years (ex work delivery) at Supplier’s care for furtherSamprogetti investigation.

4.2.18 All tests described below (macrographic and micrographic examination, corrosion test, flaw

assessment, etc.) shall be performed and certified by a laboratory approved by Snamprogetti.Laboratory shall officially inform Snamprogetti about any inconvenience (e.g. deviations fromthe material requirements etc.) encountered during the tests as well as in case of re-testing.

4.3 Microstructure examination

4.3.1 The material (base, welds and weld overlay) used in contact with the process fluid shall besubject to metallographic analysis following the methods detailed below. 3 (three)metallographic specimens, each for any required etching, shall be obtained from each of the

sample(s) as detailed in para. 4.2.2 and 4.2.10. A fourth specimen shall be retained for re-testing (if required). The re-use of the same metallographic specimen for two or more differentetchings is not allowed.

4.3.2 The metallography shall be considered preliminary to the corrosion test.

4.3.3 Presence of ferrite shall be evaluated by means of a ferritometer on each of the 3 specimensbefore etching. Ferrite content shall not be greater than 0.6 % in all specimens except forSMAW welds for which 1% is allowed.

4.3.4 The material microstructure shall be determined following ASTM A262 Practice A. Only a fullyaustenitic step structure as defined in the above standard shall be considered acceptable. Thepresence of any structure other than the step structure (e.g. ditch structure, interdendriticditches, end-grain pitting type I or II) is not allowed.


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4.3.5 Presence of sigma phase shall be checked at 100x and 500x after electrolitic etching withNaOH 10N at 3 V and 0.5 to 1 A/cm

2 for 2 to 5 sec. Sigma phase shall be absent.

4.3.6 An etching with oxalic acid (10%, 6 V DC, 0.5 – 1 A/cm2, 15 sec.) shall be performed and the

specimen shall be examined at 100x and 500x. Presence of any intergranular or intragranularcompounds or phases other than the austenitic phase is not allowed whatever theircomposition might be and irrespective of their quantity, with the exception of the ferrite phasewithin the limits stated in para. 4.3.3.

4.3.7 The material not in compliance with the above requirements shall be rejected.

4.4 Corrosion test procedure

4.4.1 The corrosion test, Huey type, shall be performed on the sample material that already resultedacceptable after the microstructure examination detailed in para 4.3.

4.4.2 AISI 316L UG specimens shall be subjected to 5 test periods and the acid shall be renewedeach time. Each period shall last 48 hours actual boiling. 25Cr-22Ni-2Mo alloy shall besubjected to 10 test periods at the same conditions as above.

4.4.3 The corrosion test shall shall follow the ASTM A262 Practice C with the following additions:

4.4.4 Only one specimen shall be tested in each flask.

4.4.5 A finger type refrigerator shall be used and it is necessary to check, by litmus paper, that noacid vapours are released during testing.

4.4.6 The ratio of the solution volume to the sample area shall be 20 ml/cm² as a minimum.

4.4.7 The flasks for Huey test shall be used only for this purpose.

4.4.8 The flask, refrigerator and specimen shall be carefully rinsed after each test cycle to remove allthe corrosion products (by means of a nonmetallic brush).

4.4.9 Before corrosion testing, the specimens shall be first degreased in acetone (chlorinated agents

are not allowed), pickled in boiling nitric acid (65%) for thirty minutes, and then rinsed; thecorrosion products shall be removed by nonmetallic brush.

4.4.10 After each test cycle and after rinsing, the specimens shall be dipped in acetone, dried by hotair, and weighed (when cold).

4.4.11 The time between two cycles shall be as short as possible.

4.4.12 Besides the determination of the corrosion rate (for each cycle and for the overall periods)obtained by weighting, it is also required to determine the maximum depth of attack byexamining under a microscope the edges of a specimen section (for details see note 5 of tablein para. 4.4.13)


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4.4.13 The following table shows both the maximum corrosion rate and depht of attack allowed ineach test cycle and for the average of the results of all cycles, calculated according to ASTMA262 Practice C:

Semifinishedproduct

Type ofmaterial

Corrosionrate

(mm/month)

Depth ofattack

(micron)

Plates, sheets,bars,tubes, pipes,

forgings

316L UG

25Cr-22Ni-2Mo

0.025 (1) (2)

0.015 (1) (2)

90 (4) (5)

70 (4) (5)

Welds andW.O. surfacing

316L UG

25Cr-22Ni-2Mo

0.025 (1) (3) (4)

0.015 (1) (3) (4)

90 (3) (4) (5)

70 (3) (4) (5)

NOTES General: the above limits are valid for each test cycle and for the averageof the results of all cycles.

(1) If the corrosion rate exceeds the rate specified in the table or if thecorrosion rate in cycle 5 (cycle 10 for 25Cr-22Ni-2Mo alloy) exceedsthe one in cycle 4 (cycle 9 for 25Cr-22Ni-2Mo alloy) by more than 50%,a second specimen taken from the same sample under examinationshall be re-tested with the same procedure. Only the result of re-testingshall be taken into consideration. Further re-testings are not allowed.

(2) No deviations allowed.

(3) The heat affected zone and the bead overlap zone (for W.O.) shall alsobe examined.

(4) Any deviation shall be subject to Snamprogetti’s acceptance.

(5) Depht of attack shall be determined after completion of the corrosiontest by taking a metallographic sample from the most corroded area, ifvisible. The value shall be reffered to the deepest attack observed onboth the transverse and the longitudinal directions of the specimen.


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4.5 Flaw assessment test

4.5.1 Samples to be tested shall be prepared in accordance with Attachment 9 (ProcedureQualification Record) and Attachment 10 (production mock-up).

4.5.2 The tube protusion shall be machined down until the contact between tube face and the upperweld toe. This surface shall be recorded as starting test level. The examination shall proceedon repeated plane at 1 mm distance from each other till the tube gets lose.

4.5.3 Each level shall be prepared for etching and examined under a binocular microscope withmagnification from x15 to x25.

4.5.4 The following table gives the number and extension of the allowable defects:

Defect type Max. allowed number ofdefects (1)

Max. dimensions allowed

Cracks (2) 0 -

Pores 5 0.6

Wormholes 0 -

Slag inclusions 2 0.6

Fusion defects 2 2

Crater cracks 0 -

Burn through 0 -

Note 1: It is the sum of all defects found on 7 tube welds at all levels

Note 2: Any deviation shall be subject to Snamprogetti’s acceptance

4.5.5 The weld fusion depht shall have a regular profile and its extension shall never exceed the 75% of the wall tube thickness at any point

4.5.6 No more than 1 defect per tube and per level is allowed. Any deviation shall be subject toSnamprogetti’s acceptance.

4.5.7 Defects extended on different levels are not allowed.

4.5.8 A photograph shall be taken on each surface (scale 1:1) showing defects location, type andextension.

4.5.9 Certification of the flaw assessment test shall be in accordance with para. 4.6.


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5 WELDING

5.1 Weldings and weld overlays shall be performed with special filler materials, low ferrite type,approved by Snamprogetti. The approved filler materials for both 316L UG and 25Cr-22Ni-2Moalloys are listed below. Different filler materials or wire/strip–flux combination shall not be usedunless approved by Snamprogetti.

316L UG CLASS 25Cr-22Ni-2Mo

Electrodes

•(Avesta) P6•(Thyssen) Thermanit 19/15 H•(Kobe Steel) NC 316 MF•(ESAB) 316 KCR•(Siderotermica) CITOXID B 316 LM

•(VEW) FOX EASN 25 M•(Thyssen) Thermanit 25 / 22 H•(Soudometal) Soudinox LF•(Kobe Steel) NC 310 MF•(Esab) FILARC BM 310 Mo L

Wires

•(Thyssen) Thermanit 19/15 H

•(Kobe Steel) no. 4051

•(Siderotermica) Siderfil 316 LM

•(Thyssen) Thermanit 25/22 H

•(Kobe Steel) TGS 310 MF

•(Sandvik) 25-22-2 L Mn

•(VEW) FOX EASN 25 MIG

Strips

•(Sandvik) 20-16-3 L Mn with(Soudometal) 12 b 316 LFT 2 flux

•(Thyssen) 21.17.E with (Soudometal)Rekord 13 BLFT flux

•(Sandvik) 25-22-2 L Mn with(Soudometal) Rekord 13 BLFT flux orwith (Sandvik) 31S flux

•(Sandvik) 25-22-2 L Mn with(Sandvik) 37 S flux (electroslag)

•(Thyssen) 25-22 H with (Soudometal)EST 122 flux (electroslag)

General note: the materials of class 25Cr-22Ni-2Mo can be used for welding of materials ofclass 316L UG.


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5.2 WPS/PQR applicable codes and additional required tests are summarized in the followingtable:

Weld Overlay

SpecimenSample S1

Sample

S2

Sample

S3

Butt jointsTube to

tubesheetjoints

Applicable code (1) - ASME IX ASME IXASME VIII Div. 2

Art. F3

Corrosion test B YES (para. 4.4) NO NO YES (para. 4.4) YES (para. 4.4)Chemical analysis D YES (para. 3.1.3 and 3.1.4) NO NO

Microstructureexamination

A YES (para. 4.3) YES (para. 4.3) YES (para. 4.3)

Macroexamination C YES (2) NO NO YES (3) YES (para. 4.2.13)

Flaw test E NO NO YES (para. 4.5)

NOTES: (1) Unless otherwise specified in the design code indicated in the purchase order.

(2) For W.O. the macroexamination shall be performed only on sample S1. The purpose ofmacroetching is to identify the sequence of the weld beads overlay and the location of theheat affected region of each weld pass, due to the re-heating during the application of the

subsequent pass. Specimen ‘B’ shall be taken out by the laboratory across the centerlineof the above mentioned area (see Attachment 2).

(3) Macroexamination to be performed to check weld structure, presence of slag porosity andcracks in weld and heat affected zone.

5.3 PQR shall include the certification detailed in para. 4.6.


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5.4 In addition to the provisions of the applicable codes the validity of the PQR is five years fromissue date and the following essential variables, if modified from what qualified during theProcedure Qualification Record as indicated in the following tables, require the weldingqualification tests to be repeated:

PRESSURE/ NOT PRESSURE RETAINING WELDS

BUTT AND FILLET WELD

ACCEPTED WELDING PROCESSES

VARIABLES

Shielded Metal Arc Welding Gas Tungsten Arc Welding

Heat input Heat input or volume of the weld metal increased more than 10%

Interpass An increase of interpass temperature

Welding position A change in the welding position (a PQR done in 3G-5G-6G-vertical-uphill

progression qualify all other position except vertical-down progression)

Filler metal size A change in filler metal size

Filler metals A change in the type, manufacturer of filler metal and/or trade name


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CORROSION RESISTANT WELD OVERLAY

ACCEPTED WELDING PROCESS

VARIABLES Submerged Arc

Welding

Electroslag

welding

Gas

Tungsten Arc

Welding

Shielded metal arc

welding

Base Metal A change in the P or Gr number

Base Metal thickness A change of±30 % in the base metal thickness

Welding current

intensity

A change of±10% A change of

±5%

A change of

±10%

Not required

Current density(A/mm

2) (strip welding)

A change of±10% A change of±5%

Not required

Arc voltage A change of±10% Not required

Welding speed A change of±5% Not Required

Heat input An increase of heat input more than what qualified Heat input or volume

of the weld metal

increase more than

5%

Stick-out A change ±2.5% of the strip/wire stick-out with respect to PQR

A change±2.5% of the

strip/wire

stick-out with

respect to

PQR (for

machine/

automatic

process)

Not applicable

Preheat and interpass A change in the preheat±25°C (first layer) and/or an increase of interpass temperature

(all layers)


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CORROSION RESISTANT WELD OVERLAY

ACCEPTED WELDING PROCESS

VARIABLES Submerged Arc

Welding

Electroslag

welding

Gas Tungsten

Arc Welding

Shielded metal

arc welding

PWHT (on first layer) A change in the temperature (±15°C)

Bead overlap A change +20%/ -0% of the overlap of

adjacent beads with respect to that

measured on PQR (applicable to firstand last layers)

A change +20%/ -

0% of the overlap

of adjacent beadswith respect to that

measured on PQR

(applicable to first

and last layers (for

machine/

automatic process)

N/A

Bead width A change +20%/ -0% of the bead width

with respect to that measured on PQR

(applicable to first and last layers)

A change +20%/ -

0% of the bead

width with respect

to that measured

on PQR

(applicable to first

and last layers (for

machine/

automatic process)

N/A

Welding position A change in the welding position

Filler metal size and/

or thickness

A change in filler metal size and/or thickness

Layer thickness (to be

specified in WPS/

PQR)

An increase in layer thickness (applicable to each layer)

Number of weld layers A decrease in the number of weld layers with respect to PQR

Filler metals A change in the type, manufacturer and/or trade name

Flux A change in the type, manufacturer

and/or trade name

Not applicable


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TUBE TO TUBESHEET WELDING

ACCEPTED WELDING PROCESSVARIABLES

Orbital Gas Tungsten Arc Welding

Manufacturer, type/ model

of welding machine

A change of manufacturer, type/model of welding machine to another.

Welding program

(supplementary document

to be attached to the

WPS)

A change in any data included in the supplementary document specifying all

applicable equipment settings (pre-gas/post-gas/welding parameter for each

sector/etc.) to assure a consistent performance.

Base Metal: Tubesheet(solid, W.O. or clad), Tube

(internal or external)

A change in the base metal type, grade or product form

Tubesheet (solid pressure

containment parts)

A change of±30% in the tubesheet (solid pressure containment parts) metal

thickness

Tubesheet (W.O., clad) A decrease in the layer number and/or increase of layer thickness.

Shielding/Backing(inside

tube gas)/Trailing gas

A change/deletion in the gas composition and flow rate used

Tubes A change in the manufacturer, wall thickness or diameter

Tube holes A change in the pitch

Clearance between tubes

and tube holes

The clearance between the outside surface of the tubes and the inside surfaces of

the tube holes shall not exceed clearance used in the welding qualification tests

Positioning system A change in the positioning/centering system of the weld head on the tube sheet

Non fusible electrodes A change in the type, size, tips shape/angle, protrusion from the torch

Welding position A change in the welding position

Filler metal size A change in filler metal size

Tubes protrusion A change in the tube protrusion form tubesheet

Filler metals A change in the type, manufacturer and/or trade name

Interpass An increase of interpass temperature


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5.5 The root pass on pipe butt joints shall be carried out by argon gas welding and with backing gasinside the pipe.

5.6 Weld overlays shall be performed with at least two layers in the case of automatic process,(except strip weld overlay on liner plates) and at least three layers in the case of manual welding:in any case, at least two layers shall be performed with low ferrite filler in compliance with para.5.1.

5.7 Stress relieving heat treatment shall be carried out after first barrier layer before to start with thefurther corrosion resistant layer.

5.8 The weld face in contact with the process fluid shall be adequately smooth, free from undercuts or

defects.

5.9 No grinding will be allowed, except on tube sheets or for removing local defects or discontinuities.

5.10 Care shall be taken during fabrication to avoid iron contamination of the austenitic surfaces bytools (grinding wheels, brushes, clamps, etc.).

5.11 The grinding wheels must not have been previously used on ferritic steels and the brushes musthave austenitic stainless steel wires.

5.12 Weld overlay deposit on 25Cr-22Ni-2Mo liner plates shall be performed by providing a forcedback water cooling circulation system during weld operations in order to keep interpasstemperatures lower than 50°C. Automatic interpass temperature control shall be adopted.

5.13 Electrodes for manual welding or weld overlay shall have a diameter not greater than 4 mm(preferably 3.25 mm max.) and, where possible, shall be used with stringer bead technique.

5.14 All the welds of internal parts to the lining shall be performed by full-penetration weldingprocedure.


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6 ADDITIONAL TESTS ON MATERIALS

6.1 Workshop check of ferrite

In addition to the requirements of para 4.3.3 the ferrite content shall also be checked in theworkshop by magnetic permeability measurement by means of appropriate portable equipmentpreviously calibrated and certified per AWS A4.2. An annual calibration certification shall beavailable to the Snamprogetti inspector. Prior to use in production, instrument calibration shallbe verified with IIW secondary weld metal standards (0 - 15 % ferrite range).This check shall be carried out on each plate or forging and on at least one every 50 pipes ortubes from the same heat and heat treatment and on one bolt and one nut for every lot andevery size from the same heat and heat treatment (for definition of “same heat treatment see

Note 1 in para. 4.1).

6.2 Non Destructive Examinations

6.2.1 The tubes for heat exchangers shall be 100% tested with ultrasonics and eddy currents inaccordance with ASTM A 450.

6.2.2 For eddy current test the calibration tube shall contain all the following discontinuities toestablish the minimum degree of sensitivity for rejection of tubes:

- a longitudinal notch on a radial plane parallel to the tube axis on the outside surface,having a length of 6.35 mm, maximum width 0.8 mm, and depth 10% of the tubethickness but not less than 0.1 mm.

- a circumferential notch on a transverse plane to the longitudinal axis of the tube, having adepth of 10% of the tube thickness but not less than 0.1 mm.

- Three or more through holes, equally spaced circumferentially around the tube andlongitudinally separated by a sufficient distance to allow distinct identification of the signalfrom each hole. The diameter of hole shall not be larger than 0.8 mm.

6.2.3 For ultrasonic examination, the calibration tube shall contain all the following discontinuities toestablish the minimum degree of sensitivity for rejection of tubes:

- a longitudinal notch on a radial plane parallel to the tube centre line, having a depth 5% of

the tube thickness but not less than 0.1 mm; on both the outside and inside surface

- a transverse notch, tangent to the surface and perpendicular to the longitudinal centre lineof the tube, having a depth 5% of the tube thickness but not less than 0.1 mm., on boththe outside and inside surface


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7 TESTS ON PRODUCTION WELDS AND CONSUMABLES

7.1 General

7.1.1 Welding consumables (electrodes, wires, rods, strips and fluxes) shall be certified for thedifferent heats/lots according to EN 10204 type 3.1.B. Snamprogetti and the owner reservesthe right to request a chemical check analysis on production welds.

7.1.2 Butt welds shall be fully radiographed (if physically feasible).

7.1.3 All welds and weld overlay deposit top layer shall be examined by dye penetrants, if possibleon the side in contact with the process fluid or, if this is impracticable, on the outside.

7.1.4 After final machining (if any) the last tubesheet W.O. layer deposited shall have a minimumthickness of 3 mm. Along this thickness the chemical composition shall be in compliance withthe requirements of para. 3.1.3. Supplier shall maintain full traceability of fulfiment of thisrequirement. Traceability data sheet shall be submitted to Snamprogetti inspector for review.

7.1.5 If the above requirement cannot be warranted by the supplier an additional weld overlay layer,other than that qualified on PQR, shall be deposited.

7.1.6 After machining of tubesheet weld overlay and before drilling operations a chemical sampleshall be taken as per Attachment 8.

7.1.7 All the welds of internal parts to the lining shall be examined by dye penetrants after eachwelding pass.

7.2 Tube to tubesheet weld production mock up

7.2.1 Supplier shall provide no. 3 representatives production mock-up to verify the tube to tubesheetweld as per Attachment 9 and 10.

7.2.2 Mock-up shall be realised applying the same production tube sheet configuration, materials

and welding parameters except for the carbon steel plate material on which the thicknessshould be reduced to a value equal at least the 30% of the original.

7.2.3 The frequency welding cycle verification shall be as follows:

a) No. 1 mock-up before starting any production weldsb) No. 1 mock-up around middle productionc) No. 1 mock-up before completion of the last 100 welds

7.2.4 On the mock-up 7.2.3 (a) an additional impediment shall be located in order to simulate theperipheral tubesheet configuration (see Attachment 10).

7.2.5 Each tube samples shall have a minimum lenght of 100 mm.


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ATTACHMENT 1


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ATTACHMENT 2


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ATTACHMENT 3


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ATTACHMENT 4


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ATTACHMENT 7

The arrows indicate the sectioning planes


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ATTACHMENT 8


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ATTACHMENT 9

Tubes To Tube Sheet Welds Qualification Procedure Test


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ATTACHMENT 10

Documents

SPC CR UR 510 3 (Important)