boiler pressure test

[daveclm]

hi
nearly finished my boiler now, and done a Hydraulic test to 2x working pressure, but after looking on the on some off the sites some do a (live steam) test to twice the working pressure, is this correct.
seam to defeat the object off the hydraulic test.

thanks dave.

[crueby]

I've only done, or heard anyone doing, a static hydraulic test to 2x.  Sometimes 3x. I would not be comfortable doing live steam that high, failure could be very bad that high with steam. As you say, the nice part with the hydraulic test is that failure is safer to experience.

[Dan Rowe]

A normal hydro test is usually twice the working pressure, but it does depend on the regulation where you live.

A live steam test should be done at FULL firing rate the safety valve should not let the boiler get more than 10% above the design working pressure.

Dan

[10KPete]

There are three tests that I know of:

1) Hydro to 2x design working pressure.

2) Steam to design working pressure, full firing, to make sure safeties will pass full volume. This is actually a check of the safeties.

3) Steam to 1.5x design working pressure, plus 2) above, annually.

Pete

[Zephyrin]

With this type of small boiler, a too high pressure test , I would say greater than 8 bar (115psi) , will inflate the boiler and irreversible bulging can occur, particularly on the front and rear face, making the fitting of the water gauge difficult etc...
Leaving the pressure overnight certainly helps to recover the hardeness of the copper, softened by the brazing steps, and would protect this beautiful boiler from dents.

[RoyG]

I don't like the sound of the suggestions that the boiler be steamed to twice rated pressure as part of the testing.  I wouldn't want to be any where near it when that 2x steam test was done.    If local Steam Boiler Regulations require a 2 x Steam Test on that size and type of boiler, then likely the Local Boiler Regulations also specify a heavier grade of construction designed to safely withstand the 2 x Rated Steam Pressure.

For a whole heap of useful and tested information, get yourself a copy of this excellent book.....   I bought a copy some time ago, and the information it contains on these small copper boilers is invaluable.  (I have no relationship with wither the Authors, or the book seller - I'm just a heppy customer.)



https://www.camdenmin.co.uk/collections/digital-books/products/building-small-boilers-for-gas-firing

The book is available as a Digital Download - UK Pounds 10.00 less the VAT, which you won't have to pay if you live outside of the UK - so about US$ 10.00.

Hope that info helps.

Blanik

[SandCam]

Hi Dave,

Looks like you have made a nice job of that boiler... well done.

Since you are in the UK the test requirements are: -

Hydraulic test to 2 x max working pressure... held for 20 minutes with no loss of pressure and with no external fitting attached other than the test pressure gauge (which must be a calibrated and certified gauge).

All fittings should then be attached except for the safety valve and the boiler hydraulically tested to 1.5 times working pressure... again no leaks shall be accepted and the pressure held for 20 minutes.
The safety valve should be set and calibrated against the test gauge and locked.

A steam test shall then be performed with all external fittings attached (and with the calibrated safety valve installed) with maximum burner and the safety valve should release at, or just below, the set pressure and check shall be made to ensure the pressure does not rise more than 10% above max working pressure (or the release pressure of the safety valve if this was deliberately set at a lower pressure) the water gauge shall be checked to see that it gives clear indication of the water level.
This water gauge can have a blow down fitted and if so then it should be operated whilst under full steam pressure and the water level should return immediately to the correct level when the blow down is closed again.
If a blow down is not fitted then the boiler shall be tipped so that the water level drops below the lower glass level and then checked to see if it returns immediately the boiler is leveled again.
The boilers small pressure gauge should be marked with a red line at the working pressure (as verified by the test pressure gauge) by the test inspector/engineer carrying out the test.
When all these test have been successful then you boiler can be certificated.

The hydraulic tests are valid for 4 years and subsequent repeat tests will only require to be done at 1.5 times working pressure. (unless any repair work has to be done to the boiler barrel assembly... in which case the whole 2x and 1.5x tests will need to be repeated.

The steam test is valid for 12 months and must be repeated annually.

I hope this clears things up for you... I assume you are able to get to a suitable model engineering club where they should have a boiler test engineer.

Good luck.

Sandy.

[daveclm]

hi
would just like to thank you all especially sandy for your very helpful information, much appreciated. some off the stuff on the internet throws you a bit.

thanks dave........

[steam guy willy]

some very neat silver soldering there, so no need to take it to the Assay office !! loverly work....
Willbert.......

[steamer]

Thank you Sandy!!!

Dave