Hello dear,

Due to a deviation in my project, wear pads that used for trunnion supports have not been worked same as thickness as attached pipes, for example where thickness of LTCS pipe material is 30.6mm, thickness of trunnion's wear pad have been used, is sch STD(Thk. 10mm).
Waht is your opinion about this matter and its consequence?

Best Regards

As reinforcement pad thickness goes down, SIFs go up, stresses go up, high forces on reinforced branch connections must go down to meet code stresses.

Whether that comes in the form of low friction supports, enhanced flexibility in pipe routing, or expansion joints - that will depend on the individual case.

Alternatively, you should argue the cost-savings case on specifying a thicker wear pad at selected locations.

Are they reinforcing all connections? If so, that might be why they're specifying thinner reinforcement pads across the board.

Dear Mr. Fletcher

Thank you four your reply but my question is about the attached wear pad under pipe for trunnion support installing exactly, now, what is your opinion about this matter.

Yours Sincerely

If the pad attached to the trunnion works on the structure as wear pad I do not think there is a problem as long as the load can be taken by the the combination of pipe and pad. This calculation is the structural calculation under either line or point contact. You, as pipe stress/support engineer, are responsible to check the stress.

If you are asking this question, you are obviously not a pipe stress or support engineer. I suggest you to talk to the responsible person who made the change, and find out the reason of the change and supporting calculations.

I misinterpreted the original message.

The worst case is you run the risk of more failures of structural steel. The typical risk of that is causing them to sag locally, where your pipe is going to have a tendency to settle to the lowest point, laterally and vertically.

If the pipe is large enough, the adjacent pipes will now gravitate towards your pipe.

Dear Mr. Fletcher

I'm confused by your answer.
Can you please review the below pdf to better understand my purpose of the question.

http://expirebox.com/download/6d9c6aca7177d12871a49a067ab819ff.html

You should be presenting this picture with your earlier question. Therefore we understood something that is not in your mind. The plate that you highlighted is called stiffener plate not a wear plate.

There are applications that the trunnion is welded on to the pipe/pipe elbows on one side with reinforcing plate and supported by structure on the other side. If you use additional reinforcement pad attachment on the pipe in contact with structural member to reduce the contact stress on the pipe, this pad may be called a wear plate since it may be moving under the thermal loads. Or sometimes the contact stresses are high on the bare pipe, and you can introduce a wear plate to reduce the contact stresses similar to the structural side application on the pipe above.

So in your case the pipe stress/pipe support engineer needs to prove that the secondary stresses on the pipe with reinforcement plate are also adequate with the selected reinforcing pad wall thickness in addition to the adequacy of the trunnion itself to comply with structural code that you are using. So the second paragraph in my previous post is still valid.

Unfortunately our industry suffers from a lack of universal terminology - let's stick with CAESAR terminology.

CAESAR would call this a reinforced tee. While yours is drawn as a filleted rectangle - and you can certainly run an FEA on this type of connection should you choose, for purposes of CAESAR analysis, we'd treat the reinforcement pad as a circle of a radius of half of the shorter end of your rectangle.

My original response stands.

In regards to my second response, I thought you might have instead been referring to a plate that's welded to structural steel and is e.g. under a horizontal trunnion support. Disregard it as it is now inapplicable.