Sulphide Stress (SSC) and Chloride Stress Cracking (CSC) corrosion requirement
perumal govindan
Please clarify the below mentioned particulars,
we have carried out a SDSS PQR with 12" Dia. x 8.38mm thick, matl.
grade: ASTM A 928 Cl.1 (UNS S32760), thickness qualified range: 8.38mm
to 16.76mm - carried out corrosion tests (like, pitting, crevice,
chloride stress and sulphide stress), all physical and chemical tests
are passed.
Hence for covering the thickness range, we have also carried out a PQR
with 4" Dia. x 3.05mm, matl. grade: ASTM A790 (UNS S32750), qualified
thickness range: 1.525mm to 6.1 mm. Here we got stuck up due to
Sulphide stress (test as per NACE TM-0177)and chloride stress (test as
per ASTM G-36) due to lower specimen thickness. As per NACE TM-0177
the minimum reqd. thickness for sulphide stress corrosion test is
3.81mm.
Now my PMC/Client is insisting to carry out the SSC corrosion test
also in 4" Dia. x 3.05mm PQR test coupon. (Filler wire used: ER 2594,
same batch & Lot Number used also in 12" Dia. x 8.38 mm)
Hence, kindly advise me that whether SSC test is required for the 4"
Dia. specimen or not.
Thanking You.
Govin
deva m
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pgoswami
Hi Perumal,
It's not clear what're the project technical requirements. However the testing requirements definitely indicate the intended application is for offshore. There are not many scopes of error in the offshore services.
As per the query posted below, the PQR on lower thickness i.e 3.05 mm would also require corrosion testing.
One may use filler wires of same chemistry, same batch or Lot No etc. But how abut the base metal ??? Does 3.05mm and 8.38 mm belong to the same heat No?
I glanced though NACE TM-0177-2005.It looks like Method-B, i.e, Bent Beam method would be the most appropriate method for piping of such lesser wall thickness.
I would think you need to discuss the issue with the Laboratory carrying out this test and your client and the independent(Third Party) inspector.
Let me know if it helps.
Thanks.
Pradip
Goswami,P.Eng.IWE
Welding & Metallurgical Specialist
Ontario,
Canada.
Email-p...@sympatico.ca,
pgos...@quickclic.net
pgoswami
Hi Perumal,
It's not clear what're the project technical requirements. However the testing requirements definitely indicate the intended application is for offshore. There are not many scopes of error in the offshore services.
As per the query posted below, the PQR on lower thickness i.e 3.05 mm would also require corrosion testing, as per the design basis specifications or clients's specifications.
One may use filler wires of same chemistry, same batch or Lot No etc. But how abut the base metal ??? Does 3.05mm and 8.38 mm belong to the same heat No? If not then the corrosion resistance would not be the same.
I glanced though NACE TM-0177-2005.It looks like Method-B, i.e, Bent Beam method would be the most appropriate method for piping of such lesser wall thickness.
I would think you need to discuss the issue with the Laboratory carrying out this test and your client and the independent(Third Party) inspector.
Let me know if it helps.
Thanks.
Pradip
Goswami,P.Eng.IWE
Welding & Metallurgical Specialist
Ontario,
Canada.
Email-p...@sympatico.ca,
pgos...@quickclic.net
-----Original
Message-----
From: material...@googlegroups.com [mailto:material...@googlegroups.com]
On Behalf Of perumal govindan
Sent: Tuesday, June 05, 2012 12:43 AM
To:
material...@googlegroups.com
Subject: [MW:14464] Sulphide Stress (SSC)
and Chloride Stress Cracking (CSC) corrosion requirement
Vinayak Kale
Not required
Regards
Vinayak Kale
OGSP - QA & I , HC - Upstream
EPC Block , 2nd Floor , Gate No.1
Saki Vihar Rd. Powai Campus
Mumbai - 400072
Ph : + 91 022 6705 3969
(M) - 9987875309
www.larsen toubro.com
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praveen alavandar
The SSC/SCC test environment is not going to change for both 12" x 8.38mm and 4" x 3.05mm materials,
You can try to justify your stand point by the following exercise,
1. Compare your pitting and crevice corrosion test results and see which has given the best result.
2. Check the heat input and interpass temp.recorded on the respective PQRs for 12" x 8.38mm and 4" x 3.05mm materials, which one has recorded the lowest.
3. Check your base material chemistry from the test certificates and calculate the PREN values for both 12" x 8.38 and 4" x 3.05mm materials, particularly check the N% of 4" x 3.05mm material, if its higher than 12" x 8.38mm material then it is better.
If all the above comes out positive for the 4" x 3.05mm material then there is a good chance that 4" material will perform better in your SSC/SCC testing.
Finally if TM0177 doesn't permit for 3.05mm thick, ask you client for the code / standard reference for conducting SSC/SCC testing on 4" material and acceptance criteria for the same.
Regards,
Praveen
--- On Tue, 6/5/12, perumal govindan <perumal...@gmail.com> wrote: