The issue of drilling leak detection holes in stainless steel-lined equipment
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There is a tower unit with a design pressure of 2.8 MPa; the medium used is fatty acids. The cylinder is made of 16 mm thick Q345R material, with a 4 mm thick stainless steel lining. The customer now requests that M12 leak detection holes be drilled in the cylinder. Will this have any impact on the strength of the unit? Urgent response needed
This should be fine, but in reality we can use M12 leak detection nozzles; by referring to the hole sizes of the equipment’s flange linings, the holes made in the equipment can be smaller, for example, with a diameter of 6.
With a design pressure of 2.8 MPa, having M12 leak detection holes on the cylinder body certainly has an impact on its strength, and this is not permitted by standards; the composite layer serves to provide corrosion protection, while the base layer is responsible for ensuring strength.
It can be opened; it has little impact on strength. It’s equivalent to creating a small hole in the equipment. The M12 leak detection hole is used not only for manufacturing and inspection, but also allows one to monitor whether there are any leaks in the lining while the equipment is in operation, enabling issues to be identified and resolved promptly.
Sure, make the cuts on the manhole flange when opening it. Our company has done this before, but after conducting the airtightness test, it’s necessary to seal everything with plugs. Be sure to carry out the airtightness test, as 4MM thick stainless steel can easily be punctured, resulting in many leakage points; if there are leaks during the hydrostatic test, it will be troublesome. Opening the manhole becomes difficult, and the gaskets end up being wasted as well. Hehe, we made 8 such cuts.
I know the flange can be opened; it’s for M10. I think it shouldn’t be a problem to weld it back in after testing once the cylinder body is opened.