Seamless pipe vs welded Pipe

[novice123]

In relation to process plant , Where we will prefer Seamless pipe , and where we will use Welded pipes ....?

[arcpro]

It strictly depends upon the process conditions and type of service. If the service is lethal, with high pressure and high temperature conditions and requiring stringent inspection checks, non-destructive testing than going for the seamless pipe is the right option. But in actual it depends upon the designer how he takes it as code does not specifies any restrictions in using seamless or welded pipes. It's the job of the designer.
Normally, in process plants, seamless piping is used for pressure rating above 600 pounds. Additionally, corrosive services should also be handled in seamless piping in order to minimize HAZ areas of stainless steel piping. There are many other factors also.

[novice123]

Is stainless steel welded pipe exists.............if No ...why........Is there any specific reasons..........?

[arcpro]

Yes, you can see ASTM A358 standard for welded stainless steel pipes. Readily available.

[novice123]

Thnx for useful information.............. whats factor we will consider in making a decision whether to use SS or CS......?

[arcpro]

Dear Novice123,
It would be good if you post this question regarding CS or SS in Project Engineers or Inspection & Reliability Forum.
Thanks for understanding.

[novice123]

What is the cost comparison of Seamless pipe and welded pipe of same diameter?

Regards

[arcpro]

Seamless pipe in the same diameter and the same material would not be costing more than 20% of the diameter is > 14".
It depends upon the ASTM standard to be followed which describes the extent of examination to be made of welding and of course the welding type.

[mechcolor]

Principally ASTM or other material standard drives the cost.

[alzuhd]

a seamless pipe is the standard for a pipe less than 12" dia and could still be obtained for sizes up to 24"
larger sizes are difficult to obtain

welded pipe may result in risks of additional flaws associated with welding
however improved welding technologies is ever reducing the impact of these risks as welding becomes more reliable

apart from lethal/ sour service conditions carbon content plays a great role in preference of seamless to a welded pipe , formulas are given in the relevant ASME code