Pipe fabricated with ends milled for horizontal deviation

Question

Pipe fabricated with ends milled for horizontal deviation

Freddy73 (Mechanical)

(OP)

12 Nov 01 14:18

Can anybody help me?

How can I to verify if a installed piping system it is safe, when for a change horizontal direction in a section, was made joining both ends pipes milled for obtaining a deviation of 11 horizontal degree without the use of any fitting. The dates of pipe are:
24”Ø, 0.875” wall thickness, Design pressure: 739 psi, Operation temperature: 174 degree F;
And if the installation is no safe, what must I do?

prex (Structural) · Answer 1 · 2001-11-13 12:57:10

What you have is a kind of miter bend.
To my knowledge this doesn't require any higher thickness than straight pipe.
In ASME B31.1 you find the stress intensification factor for miters, that however matters only for expansion stresses.

prex
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jmagee (Mechanical) · Answer 2 · 2001-11-14 11:45:15

The response form "prex" is correct assuming that your design conditions are B31.1, however, you still need to have the reinforcement checked due to cutting the hole in the run pipe. The area removed must be replaced by the attaching pipe. If the attaching pipe does not have enough area for reinforcment, then you have to install a saddle or some other type of O-Let fitting to gain the required 100% area replacement.

kstaylor (Mechanical) · Answer 3 · 2001-11-14 19:36:43

ASME B31.3 outlines a method for calculating the required thickness for mitered joints. This method usually results in a greater thickness for the mitered section than for unmitered straight pipe, however. One recent job that we had mitered sections on resulted in the mitered sections being about 1.75" thick, while the straight sections were on the order of 1.125" thick for the same design conditions and diameters.

You really need to pay attention to which Code the piping is designed to.

jmagee (Mechanical) · Answer 4 · 2001-11-15 09:36:57

I agree with kstaylor,
first and formost, the main issue will be the code and all of the design conditions.

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Pipe fabricated with ends milled for horizontal deviation