This refers to our T.Van Laan's Pipe Support System eqn 8.16clause 8.3.1.1.
There, pipe wall thickness t - what should I take - 0.875*(tpipe + twearplate)-corr allowance in computing local stress for saddle ? After adding with pipe hoop stress - which allowable will I compare with 1.5*SE as taken in WRC-107 module of Caesar-II or any higher allowable ?

regards,

sam

PS:- I posted this query for a saddle with a wearplate for supporting a preety large bore hot piping and to ascertain the allowable for local stress - DIPRA ductile iron pipe supports also gives similar expression from Roark, but does not consider inclusion of hoop stress while comparing with allowable Symin/1.5.

Hi Sam,

Unfortunately, there is not a simple yes or no answer to your question with regard to the inclusion of the wear plate in the saddle support analysis of your large bore piping.

You may be familiar with the paper "Stress in Large Cylindrical Vessels on Two Saddle Supports" by L.P. Zick. This paper discusses the local stress analysis that you are interested in. There have also been subsequent interpretations of Zick's work. Saddle stress analysis is also a topic found in many of the pressure vessel design books that are based on the original Zick paper. If your geometry falls within a certain set of parameters, the thickness of the wearplate can be included.

According to the "Steel Plate Engineering Data" publication, the wear plate thickness can be included "provided the width of the added plate equals at least (b + 10t1)", where t1 is the shell thickness. Other interpreations have other restrictions.

In conclusion, please review the literature and make your best informed decision.