Boiler Hydraulic Test Certificate

Hi all,

I was always under the impression that the test certificate that came with the boiler was valid for 4 years. As I'm rearing the end of my build I was discussing boiler testes with one of the testers at my local Model Engineering Society. He said they would not accept the manufacturers hydraulic test certificate and want do their own before I could run at the club (obviously would need steam test as well). Is this normal or is my club being awkward?

Also please could anyone give advice for preparing it for a hydraulic test as I think the club testers only really have experience of railway locomotives where it is easier to blank off the regulator etc.. I'm concerned that the regulator will let by and the only way to completely blank it off is to remove the cylinder which I obviously don't want to do. How is this normally handled?

Thanks
Ian

the test ticket is for the boiler shell if you like but you have put fittings and a cylinder on and these are now part of the test as they are part of the pressure vessel and require testing to make sure they are sound
give it a test first as the regulator may well seal but it is quite common for it to weep and your tester should know this if you leave the drain cocks open they will drip if the regulator weeps
hope this helps
mark

IanR wrote:. I'm concerned that the regulator will let by and the only way to completely blank it off is to remove the cylinder which I obviously don't want to do. How is this normally handled?

Thanks
Ian

My regulator leaks quite nicely with anything more than 50psi it ticks over rather pleasently, its got no actual power behind it as you can stop the flywheel with your little finger resting on it but I was concerned when I had my hydraulic test last year, but all we did was pop a bit of thin rubber under the regulator puck and then the safety valve blanking plate has a centre screw which pushes down on the puck to seal the reg up nicely.
My boiler inspector was quite happy with that, we did polish the puck a little while we had it out to try and seal it better when in steam but it was going to need more than a quick polish and while it improved it a little it was still letting by. Doesnt really bother me as I like the fact the engine turns over "really" slowly when in steam and I dont have to faff with the regulator to acheive it Boiler inspector was quite happy with it.

Thanks. That's reassuring. I'll be at the club on Saturday so will discuss it with them.

IanR wrote:Thanks. That's reassuring. I'll be at the club on Saturday so will discuss it with them.

Would be interested to know,please keep us informed Ian.
Have a good Christmas buddy
Steve H

Hi Steve, Will do. I'm going to take some photo's of it's current state for them to look at and hopefully get some advice on what they would want me to do for a test. Then maybe organise a 'dummy test'

Have a good Christmas yourself.

I had to have my boiler tested with no fittings on at all. This meant I had to make blanks for any holes in the boiler. I pressurised the boiler with 100psi of air and after leaving it in the summer sun for 4 hours, the pressure increased to 105.The Boiler inspector was impressed with that but still pumped it up to 150 to be sure.

chrisnchrisroberts wrote:I had to have my boiler tested with no fittings on at all. This meant I had to make blanks for any holes in the boiler. I pressurised the boiler with 100psi of air and after leaving it in the summer sun for 4 hours, the pressure increased to 105.The Boiler inspector was impressed with that but still pumped it up to 150 to be sure.

I wouldn't pressurise with just air, air is elastic and potentially dangerous, fill the boiler with water first then you can use air to pressurise it, if a problem occurs it will leak rather than explode.

chrisnchrisroberts wrote:I had to have my boiler tested with no fittings on at all.

I really hope they don't insist on this as I've already fitted the cylinder and quite a few of the fittings.

Unless you've had the boiler for years the certificate supplied by STW should be valid. The boiler inspector will want to test the integrity of all the other joints... cylinder block gasket, pipework etc.
You should never test with air or any other gas, as if you have a failure under pressure it will go bang due to the stored energy, but when using water which cannot be compressed you only need to pump in a small amount to raise the pressure, therefore if you have a joint fail you simply get a little wet. There should be a little lift on the regulator valve so you could always cut a small piece of thin rubber or nitrile sheet, put that under the valve and refit the cover, as the pressure raises during the hydraulic test the valve should seal against the rubber - I've done this on a full size Aveling roller. Just remember to take the rubber out after the test.

Its a few years since I did the hydraulic test and yes I did fill with water first.

That is why its called a hydraulic examination and not pneumatic.