Replacing Olets

[AlaskanME]

When replacing a CS 3/4" Thredolet with a 3/4" Sockolet, are there any special precautions to take? Is making up a new pup piece necessary? Run pipe size is 8" schedule 40. I know it is recommended to not weld over previously heat-affected zones in certain situations. The reason we are going through this is to slowly phase out our threaded thermal relief piping with socket welded. We may be able to seal weld the threads if cutting out the Thredolet and inserting a Sockolet is not recommended.

 

[XL83NL]

It depends.

Are looking at this from a code perspective, i.e. does the code allow this? What’s the service? Then, the ‘code’ (assuming B31.3) is only for new construction.

Are you looking at it from a mechanical perspective?

Or from a metallurgical/welding point of view?

There are various takes on this. A bit more background (service, pressure and temperature, etc.) would help.

Huub
- You never get what you expect, you only get what you inspect.

 

[AlaskanME]

Hello XL83NL,

This is a post-construction weld, so yes, 31.3 would not apply and API 570 or PCC-2 would be referenced. I am looking from a welding and mechanical point of view and wanting to know what the industry norm is when replacing Olets and nipples on process piping.

Service: Jet fuel
Operating Temp: ambient
Design Pressure: 100 psig
Construction code: ASME B31.3

Thanks

 

[Dhurjati Sen]

Why are you replacing the threadolets?

Who suggested the replacement with sockolets?

This is a case specific issue, the norms for other industries may not be applicable in your case.

Any modification has to be incorporated in the drawing by revising the original drawing. This job is to be done by the design team or the engineering services of your organisation or it needs to be outsourced.



DHURJATI SEN
Kolkata, India

 

[KevinNZ]

A boss or 1/2 coupling is a good alternative to 'olets. See what the code allows.

 

[LittleInch]

I don't believe this is a common activity and therfore there is no "norm".

Olet welding involves quite a lot of weld metal and heat and therefore the safe method is to replace the spool.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[DekDee]

What about a Sweepolet ?
That will satisfy your concerns with rewelding over the HAZ - it will be removed completely.

 

[MJCronin]

I agree with LittleInch .... This is an uncommon activity and replacement the spool seems the best course of action.... IMHO

There is significant risk of run pipe warping and other weld problems when working in a tiny area in the field

Spool replacement also allows controlled shop fabrication of sub-assemblies way ahead of time .....and therefore easier controlled welding of larger run pipe sections in the field. Also easier scheduling and job control ....

Spool replacement is far superior and appreciated by the welders, rater than working with tiny components.

The additional cost of the spool piping will probably be made up by a smoother, more accurate field installation

My opinion only ......

MJCronin
Sr. Process Engineer

 

[AlaskanME]

Thanks for the replies. I agree with your sentiments LI and MJCronin.

 

[LittleInch]

I understand the desire but have you looked at drilling the threads out to create a sockolet instead of complete replacement?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.