Strengthening calculation for connections during hydrotesting? ?
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This post was last edited by sinolion on 2012-8-21 00:02. May I ask whether it is necessary to check the reinforcement of the openings in the pipes during hydrostatic testing? Especially for those large openings, if a verification is to be carried out, how should the calculated pressure for the pipe fittings and the allowable stress for verifying large openings be determined? (The method for strengthening openings specified in GB150 is used here.) Please advise: in SW6, the opening reinforcement is not checked for hydrostatic testing; only the opening reinforcement under design conditions is checked
Let me share some preliminary thoughts: as long as the design calculations are satisfactory, it is generally not necessary to conduct pressure tests to verify the reinforcement of the openings. Just as flanges selected according to standards are not subject to pressure test verification.
In the design, the allowable stress is used as the criterion for acceptance; it is generally 1/1.5 of the yield strength. For short-duration pressure testing, 0.9 of the yield strength is used as the acceptance criterion. Generally, if the test pressure is not increased, there is no need to verify whether the stress on the equipment under pressure testing meets the required standards.
This problem arises because when large openings are made in the calculation equipment, according to ASME Appendix 1-7, the maximum membrane stress must be less than the allowable stress, and the sum of the membrane stress and bending stress must be less than 1.5 times the allowable stress. The calculation of stress is closely related to the calculated pressure of the pipe. When performing a hydrostatic test on vertical equipment in an upright position, the calculated pressure on the large connections at the bottom of the equipment is often very high, resulting in non-compliance with the requirements of ASME Appendix 1-7. In my personal view, if verification is required, the allowable stress should be 0.9 times the yield strength.
This post was last edited by liushen203 on 2013-8-12 at 18:28. Hello~ I found you through an article on using hydrostatic test values for calculating reinforcement in large towers. I would like to ask you a few questions; please add me if it’s convenient
The reinforcement for the SW6 opening has been approved, so there should be no issues with the hydrostatic test.
Verify the opening reinforcement during the hydrostatic test. You can verify this by changing the design pressure to the hydrostatic test value, and adjusting the allowable stress value of the material to 0.9 times the yield strength for the calculations