Boiler test question

Many thanks for the explanation

 

This video shows why we use water rather than a gas for pressure tests. It is a high pressure gas line not a low pressure steam locomotive boiler, so the effects are easier to see (test pressure is well over 100 barg on this pipeline)
Air or service gas tests are very dangerous and you need a large exclusion zone around what you are testing.

 

I Have a question that's very relivent, Its to do with riveting, when i have assisted with boiler work, we have always done "hot" riveting on boilers , rather than cold hydraulic, my question is this, does a hot rivet make a better pressure seal? i would think that once the end is turned over, a red hot rivet , if its done fast enough, will also contract as it cools so effecting a tighter seal , where as a cold rivet will only turn over as far as the strength of the steel or copper will allow it and you may possibly damage the plate dishing the area the rivet is in can anyone who has knowledge of this explain?

 

That is my understanding, I have only book knowledge apart from assisting with riveting at BRC. I don't really understand how a cold hydraulic process can exert the same clamping force between the plates as a contracting hot rivet.

Michael

 

plus with a red hot rivet, the pressure needed to turn over the shank will be less, so hopefully less chance of plate deflection i know that rileys used to prefer cold riveting, but i dont know if that was used on boilers, or just on frames etc,