Barred Tee - Internal Bar Material

[HurtinAlbertan]

I am looking for some guidance on the material specification to be used for internal bar stock that a client has requested to be welded on the branch connection of a 6" Sch. 80 straight tee. The line in question is an above ground riser built to CSA.Z662. The material spec of the straight tee is low temp sour service SA420-WPL6. Any advice would be greatly appreciated.

 

[SJones]

The bars don't necessarily have to be bar stock, A516 plate is a common material for the application.

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.

 

[LittleInch]

One thing you need to think about is the weld material. The last barred tee I made for a high CO2 wet gas line, when they came to replace the elbow off the tee as it had corroded too much, the bars had vanished due to weld material being preferentially eaten by the wet CO2 gas!

Personally I don't like bars as the welding is often difficult and testing is next to impossible. A set of plate bars with a long fillet weld on a spool piece which then fits on the branch is much more solid and reliable than simple bars. Something more like this

http://www.valvitalia.com/Pages/en_product_catalog.aspx?TYPE=PLANT&TAG=VALVITALIA_CHINA&PID=190

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[HurtinAlbertan]

Thanks for the info, this is great.

 

[SNORGY]

The other thing to consider is that I think Z245.11 mandates PWHT on the fitting after pig bars are welded in. Can't remember if it's mandated for a field-welded installation, but technically, if this was to ever be called upon to pass for a fitting under the CSA codes, it wouldn't - at least that's my interpretation.

 

[SNORGY]

But I agree that SA 516 70N would be suitable.