Pipe support

[MemphisDepay]

Dear all,

What kind of sheet material are used between pipe and supports to prevent crevice corrosion.

Thanks in advance

 

[bimr]

It is recommended to install a rod on the sleeper and structural support as per L.C Peng in his book "Pipe Stress Engineering". In many cases, when pipe sits on a flat metal support, moisture is trapped which leads to corrosion. The round edge of a pipe resting on the round bar prevents moisture from accumulating.

http://stoprust.com/i-rod-pipe-supports/

 

[BigInch]

Pipeline codes require full encirclement of fully pressurized pipe at supports.

It is common to see 1/2 encircling rubber pad vulcanized to the pipe bottom and placed on top of a flat topped wide flange beams, or a full encircling rubber pad vulcanized to the pipe, then a fully encircling clamp placed around the pipe/rubber pad. The clamp is then bolted to a wide flange beam.

Fully encircling plate is also seal welded all-around on the pipe. The pipe with full encirclement sleeve then is placed on a support or the support can be welded directly to the sleeve.

834 (b) If the pipe is designed to operate at a hoop stress
of 50% or more of the specified minimum yield strength,
support of the pipe shall be furnished by a member that
completely encircles it. Where it is necessary to provide
positive attachment, as at an anchor, the pipe may be
welded to the encircling member only; the support shall
be attached to the encircling member and not to the
pipe. The connection of the pipe to the encircling member shall be by continuous welds, rather than intermittent ones

A842.2.7 Design of Clamps and Supports. Clamps
and supports shall be designed such that a smooth trans-fer of loads is made from the pipeline or riser to the
supporting structure without highly localized stresses
due to stress concentrations. When members are to be
welded to the pipe they shall fully encircle the pipe and
be welded to the pipe by a full encirclement weld. The
support shall be attached to the encircling member and
not the pipe.
All welds to the pipe shall be nondestructively tested.
Clamps and supports shall be designed in accordance
with the requirements of API RP 2A-WSD, Section 3.
Clamp and support design shall consider the corrosive
effects of moisture retaining gaps and crevices and gal-vanically dissimilar metals.

Interpretation: 15-8
Subject: ASME B31.8, Para. 834.5
Date Issued: September 9, 2009
File: 07-1468
Question (1): For piping that is operating at 50% or more of SMYS, and a welded pipe support
connection is desired, is it necessary to provide a full encirclement sleeve, continuously welded
to the pipe, for attachment of the welded pipe support?
Reply (1): Yes.
Question (2): For piping that is operating at 50% or more of SMYS, is it necessary to provide
a full encirclement sleeve (welded or not welded) to the pipe when a nonwelded support connec-tion is desired (such as a clamp)?
Reply (2): No.

 

[racookpe1978]

One note of caution with supporting off of a single point (round-to-round) impact point: I've seen those rub through the pipe wall and cause leaks in drain pipes at near 0.0 static head after only a few years service at modest temperatures and low temperature changes. If at all possible, as noted above, follow the code for pressurized pipe and don't do it where rubbing will occur.

 

[MemphisDepay]

Dear all,

Thanks for your reply. Mr.BigInch can you tell what kind of rubber pads are used between the pipe and support.Any specific name for those rubber pads?

Thank you.

 

[BigInch]

Vulcanized Rubber. Looks like the same stuff tires are made of, but comes in sheets.

http://3.imimg.com/data3/JX/Phttp:/...393828O/MY-133730/abra-super-rubber-sheet.pdf

 

[surekhaajay]

In one of my ongoing offshore project, we are using 3mm PTFE pad between the pipe bottom and support top plate.

 

[bimr]

The typical sliding materials:

http://www.pipingtech.com/technical/articles/slide-plate-applications.html

 

[MemphisDepay]

Thank you friends.

 

[dobspiper]

for a 8" sch 40 fire water hydrant line we used 12mm solid rods welded to the sleeper top plate to prevent crevice corrosion.

dobspiper

 

[LittleInch]

Good to see a footballer moon lighting as a petroleum engineer...

Is there some reason you haven't used clamps and guides - it can seem to be a bit of a pain, but the long term benefits of such things are often significant.

Any soft material can wear away without becoming apparent and you need to be careful about what the stress analysis program has assumed for friction at the supports. Make it too easy to slide (PTFE or Teflon) and it could cause significant issues elsewhere in the system from pipes moving whne they weren't supposed to.

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