He says it fails occasional stresses, so I'm guessing that because it is not adequately anchored, when you model the line, the wind and/or seismic cases cause gross displacement of the line resulting in overstress.
"Inadequate support" may also mean that spans are too long and you're getting...
What kind of gas? What kind of pipe? Do you have a design code? How long is the pipe?
Design temperature is important, but we're going to need a lot more detail from you.
What is "required" depends entirely on the owner's requirements and any applicable regulations. In general, you don't have to go back and bring the line up to meet current code requirements, but you do need to determine if any of the issues you have identified are fitness for service issues...
B31.4 does not consider the manufacturing tolerance separate from design factor. 0.443" would be the Code minimum wall thickness, exclusive of any corrosion allowance.
Refer to para. 403.2.1:
"In setting design factor, due consideration has been given to and allowance has been made for the...
What is the design code?
Assuming design pressure is 1480 psig, 0.500" wall thickness is thin in the low yield flange material, but how thin will depend on your design code.
ASME PCC-2 is written a little more clearly for the design of pressure sleeves. Refer to Figure 206-3.5-2.
I would do your pressure containment calculations as you have for example 1. Note that that if your fitting has a long seam weld, your weld efficiency of that seam will be based on your...
@GD2 What am I missing?
Try running the numbers here.
If we assume this is a B31.8 pipeline, the maximum design pressure is ~875 psig, assuming the highest allowable design factor of 0.8. That results in a hydrotest pressure of 1094 psig, which is about half of the proposed test pressure here...
Am I missing something? That hydrotest pressure on that grade of low yield pipe results in hoop stress almost double the yield strength. This looks like a bomb to me.
What is the design pressure? What is the basis for the test pressure?
Those main line and kicker line sizes are in the range that I've typically seen. I've seen operators' specifications limit the kicker to no less than 1/4 of the main line diameter (so DN 50 for your DN 200 main line), and many installations are larger than that. You'll need to check fluid...
I'm guessing you are looking at an old version of B16.20 and a newer version of B16.5. The reference only works if you refer to B16.5 from around the same time as the version of B16.20 you are using.
Consider using a current version. Both standards have been significantly revised.
I interpret condition 3 to require action to prevent impact loading, if you are going to take credit for that reduction. That may mean removing small bore valves from the system or taking administrative action (like car seals) to prevent impact loading at cold temperatures, as well as guarding...
