Hi Cyril,
If this equipment is an integrally S.S clad , then you may perform weld repair as per API-510. There could be a few scenarios as explained below.
- If the corrosion is only on the clad surface:- then you may follow API-510, clause 8.1.5.4:-Repairs to Stainless Steel Weld Overlay and Cladding.Note prior to any weld repair, out gassing shall be done to remove any entrapped or any gases absorbed gases by clad and base metal.As per AWS-D-10.10 and API-945 , an acceptable outgas procedure consists of heating the area to a metal temperature of 450-600 deg F and holding at that temperature for 2 to 4 hours.Following out gassing ,repair on the clad may be performed using a qualified conventional weld overlay/clad restoration process. The email sent by Mr. Hegde(see below) explains the S.S clad repair process.
- If the corroded area penetrates on the C.S backing metal-Then there could be a number of issues:-
- Performing weld repair on the C.S base metal followed by clad restoration as above followed by PWHT. This scenario would apply if the process environment calls for PWHT as mandatory requirement.
- Alternatively API-510 allows repair on P1 material without PWHT, subject to the fact that repair would be done as "Controlled-deposition Welding Method alternative to PWHT". This technique is similar to Temperbead weld repair as described in NBIC-23, with some additional requirements as asked in API-510.
- Applicable Clauses:- 8.1.6.4.2.2:- Controlled Deposition Welding (Notch Toughness Testing Not Required), Clause-8.1.6.4.2.3 Controlled-deposition Welding Method (Notch Toughness Testing Required). Note a PQR has to be qualified as specified in the above clauses, in API-510 for performing such repair.
However if the process environment calls for mandatory PWHT then above API guidelines would not apply.
As the clad metal is S.S ,in a process environment, use of electrodes with matching chemistry would be ideal. Use of Inconel electrodes may not be required unless allowed by design specifications.
I hope the above information would provide you sufficient guidance for carrying out the repair.
Thanks
From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of hegde.pb@isgec.com
Sent: Tuesday, October 12, 2010 12:50 PM
To: materials-welding@googlegroups.com
Subject: Re: [MW:7517] Regarding Inconel Welding
I) What is the depth of corroded area. And it should not. Be in the base metal this can be detected by applying copper sulphate sol.
Ii) If the depth is with in SS material No need of using inconel and you can use the equivalent SS weld metal and also no need of PWHT
Iii_ -f it is very deep and penetratoing in base metal ': in such case you need to reapir base metal to attain the reqd base metal thickness and later carry out the restoration of welded clad If the base metal near repair is less than 38 mm you can skip PWHT however you need to have PQR of overlay with out PWHT
Regards
Hegde
Ii) I
Sent from my BlackBerry® smartphone from !DEA
From: "cyril andrews" <jcyrilandrew@gmail.com>
Sender: materials-welding@googlegroups.com
Date: Tue, 12 Oct 2010 19:13:03 +0300
To: <materials-welding@googlegroups.com>
ReplyTo: materials-welding@googlegroups.com
Subject: [MW:7514] Regarding Inconel Welding
Dear all,
Here by i am araising one question which i am in need of some clarification.
I am having a vessel to be repaired and that vessel is a carbon steel and inside with stainless steel material. That vessel is a PWHT vessel. Now we are going to repair that vessel, due to corrosion. But after welding we cannot do PWHT on that job. So i want a good suggestion to avoid the PWHT. What abt inconel welding? How it satisfies the PWHT requirement. If any one knows... please share with me. I hope i will get a good solutions.
Regards,
J.C.Andrews,
QA/QC Engineer,
Doha-Qatar.
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The views expressed/exchnaged in this group are members personel views and meant for educational purposes only, Users must take their own decisions w.r.t. applicable code/standard/contract documents.
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