Welding of Structural Steel SA-36 to pressure parts for a Vessel in Sour Service.

[TheMehanic08]

Hello All,

I am currently reviewing some drawings for a pressure vessel in sour service. The Details are as below:

Design code: ASME section VIII Div. 1
Design pressure : 10 bar
Design Temperature : 150 Deg. C
Corrosion Allowance : 3 mm
MOC : SA 516 Gr. 60
MOC of rungs : SA 36
Service : Sour Service

This vessel has a manhole and internal rungs. The handles welded to the manhole blind flange and the internal rungs welded to the shell directly are of structural grade SA-36 material.

Is this acceptable? Is there anything written in the code ASME Section VIII Div. 1 about this.

 

[marty007]

AFAIK, ASME does not address sour service. You'll have to check the NACE specs.

Marty

 

[TheMehanic08]

Thanks for the reply Marty

Well i did check NACE MR0175/ISO 15156 nothing there.

 

[SJones]

Is this acceptable?

Is what acceptable? Use of A36? Welding to the shell? Welding to the blind flange? Etc. ISO 15156 will only guide you on the particular requirements for the welds and the requirements for the ladder material should it be deemed necessary to avoid H2S damage in the ladder.

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/pub/8/83b/b04

All answers are personal opinions only and are in no way connected with any employer.

 

[TheMehanic08]

Thank you for your reply Mr. Jones,
Well I wanted to know if welding structural steel directly to a pressure part is acceptable. Are there any concers if this is done.
Cos generally as a good engineering practice we never weld a structural steel directly to a pressure part, howver in the csae mentioned above this has been done and also the pressure vessel is in Sour service.

 

[marty007]

Take a look at UG-4(b).

Here it states that non-pressure parts welded to the shell do not even need to conform to the material specifications permitted by ASME VIII-1, so long as they are of "weldable" quality (discussed in UW-5(b)).

When I first read this, it opened by eyes a little as to why there are so many other grades of steel included in ASME IX, but that are missing from ASME II-D. By excluding materials from ASME II-D, it makes it very difficult for pressure boundary use, however by including them in ASME IX you are provided an easy route to use these materials for non-pressure parts.

 

[chaulklate]

Yes, you can weld SA-36 to SA-516-60, as well as to your blind (SA-105 or SA-350-LF2, or any other P1 material for that matter). Regardless of sour service it is acceptable. Your client specs may say otherwise.

Also refer to UCS-6(b); SA-36 is not only for structural but also approved for PRESSURE PARTS with limitations.

 

[jtseng123]

We do use SA-36 for rungs and full penetration weld to vessel wall and perform WFMPT for wet sour service.

 

[TheMehanic08]

Thanks Guyzzz

 

[InspectorJohn]

As stated, you can do it. It's done all the time for ladder/platform clips, nameplate mounts, insulation support clips, etc, etc, etc.
Given the service, the client specs may have additional requirements like PWHT and/or taking Brinell hardness readings after welding, among others.