Magnetic Particle wait time

[antd15]

Our company standard for a hot tap over 2" states that magnetic particle shall be done. However, it does not state how long after the installation is complete to perform MP. I thought the standard time was after 24 hours. Is 24 hours standard?

Take into consideration that the thickness of the split sleeve is greater than 3/4".

 

[JR97]

antd15,

Most MT can be performed immediately after welding. A delay is only imposed for high strength alloys like HSLA100 etc, which have delayed hydrogen cracking concerns.

My experience with 'garden variety' steel is as soon as it is cool you can test it.

JR97

 

[hogan666]

antd15,
dry MT is typically limited to temps under 300F. The requirement for delayed inspection usually only applies to Q and T steels like A514

 

[stanweld]

antd15,
Delayed hydrogen cracking is possible in low carbon steel as well if there is sufficient thickness and joint restraint and cooling rates are sufficient to produce martensite on cooling and appropriate preheating was not performed to allow for hydrogen to diffuse into the atmosphere. The need for delays of 24 to 48 hours prior to testing is based on the alloy composition, weldment design and preheating/interpass maintenance and choice of welding process and filler metal diffusible hydrogen.

In your case, if the split sleeve welding sequence is appropriate and the materials are low carbon steel or microalloyed low carbon - manganese steels, and the process fluids do not provide a high quench rate, delayed cracking should not be expected, assuming that you are making the weld with low hydrogen processes.

You need to provide more detail as to the nature of the hot tap in order for a more precise answer