Backing Rings

By kbolles Date 11-26-2007 14:14

I work for a company that manufactures level controls for the petro/chem industry and I need some advice about backing rings as I have never used them before. These controls fill slowly and because the joint is at the top of the control, the joint will not come in contact with the process. We build to ASME B31.1 and B31.3 and from what I can ascertain I should be able to leave these rings in place because corrosion is not a great concern with this application. These controls will be welded using a Panasonic Dip Pulse HM III 350 Robotic Welder with ER70S-6 filler on an A105 ANSI Flange/A106B SMLS Pipe and the backing ring is A109. I have to qualify these welds because the company wants to increase productivity and using these backing rings should help in that area because it will eliminate the need for cleanup. Any tips, pointers or observations would be greatly appreciated.

By G.S.Crisi (****)

Date 11-26-2007 20:17

You say that the controls will be used in petrochemical and chemical industries and corrosion isn't a concern.
A word of warning: if the medium whose level they will control is strongly caustic, i.e., pH above 9, and it will come in contact with the weld (you say it won't but one never knows), then corrosion IS a concern, because the backing ring will promote caustic embrittlement.
By the way, from the description you've made, I'd think that the devices are Leveltrols, which used to be made by Fisher. Am I right?
Giovanni S. Crisi
Sao Paulo - Brazil

By kbolles Date 11-26-2007 21:45

No, we are SOR Inc. out of Lenexa Kansas, formally MSW out of Houston Texas. If the medium rises to the level of the weld then the whole control has failed and that makes caustic embrittlement moot because this weld is well above the upper process connection. I should not have wrote that corrosion is not a concern because it always is, no matter what the application. However, I have been with SOR for over 17 years and corrosion has never been the cause of a failure in the time I have been here. Thanks for your input though, it is always beneficial to hear other opinions.

K. Bolles

By G.S.Crisi (****)

Date 11-26-2007 22:38

Well, in my opinion the welding procedure is to be qualified to ASME IX.
The welder being a robot, it'll be qualified together with the procedure.
By the way, do robots need to be qualified?
Giovanni S. Crisi

By CWI555

Date 11-26-2007 23:21

B31.3
welding operator: one who operates machine or automatic
welding equipment.

Each employer is responsible for the welding done
by the personnel of his organization and, except as provided
in paras. 328.2.2 and 328.2.3, shall conduct the
tests required to qualify welding procedures, and to
qualify and as necessary requalify welders and welding
operators.

Not the machines, but technically the operator of the machine does.

Section IX 04
Reference
Para. QW-101

By 803056

Date 11-27-2007 14:14

In the wonderful world of ASME Section IX the welding procedure can be qualified by an individual using the manual process or by automatic machine. Paragraph 410.25 lists this variable as nonessential.

Best regards - Al

By js55

Date 11-27-2007 14:39

Robots do not need to be qualified. Nor should they. After all, all they are is a multi axis maniplulator.