Boiler Testing Procedure

Rydale Society Model Engineering (RSME) Limited does not undertake the testing of steel boilers (copper boilers only). For boiler testing, contact an RSMEL boiler inspector to make the necessary arrangements. (Do not just turn up).

When building a boiler, the following requirements of the boiler testers shall be adhered to as per the Boiler Test Code ‘THE EXAMINATION & TESTING OF MINIATURE STEAM BOILERS’ (Revised edition May 2018).

Together with the following requirements of RSME Ltd:

    • All boilers will be inspected by a Boiler Inspector who has been appointed by the Railway Committee of RSMEL and witnessed by a competent member of RSME Ltd.
    • For non-commercial boilers, the boiler shell, including butt straps, lap joints, and firebox assemblies are required to be inspected before inner and outer firebox assemblies are put together. If possible, a photographic record is to be made and retained in that boiler test paperwork.
    • For hydraulic tests, the safety valves should either be removed, and the orifice plugged, or some means of clamping the valves closed against the test pressure. It is considered bad practice to screw the valves down.
    • Boilers shall have a 5/16” x 32 male connection – for connecting the club’s test pump, and a ¼” x 40 male connection for connecting to the club’s test pressure gauge. Both connections should have female 60-degree cones.
    • For the initial test, all apertures shall be temporarily plugged to withstand (without weeping) the test pressure applied.
    • Any unscrewed bushes i.e., dome bushes, regulator bushes etc. that are silver soldered to the boiler shall have both the blanks and the permanent bushes fixed to the bushes using bronze, stainless steel, or Monel metal bolts. This will also apply if the fastening is in a blind hole.
    • The boiler pressure gauge shall be available for testing the day the steam test takes place, making sure the gauge is clearly indelibly marked, indicating the maximum working pressure. The standard pressure gauge siphon union nut is ¼” x 40. If by chance it is not, please advise the Inspector as to what thread it is a day or so before the test is due to take place.
    • If a boiler is presented for test at RSME Ltd. without any written history of being tested, it will be treated as a ‘New Build’ and will therefore require a shell test. This will consist of a hydraulic test at its working pressure x 2 for 15 minutes. If no loss of pressure is detected during this time it can then be steam tested as per the regulations and certified accordingly. However, if any loss of pressure is detected, the cause must be found and rectified before further testing. If no obvious external cause is found this will mean stripping the cladding off the boiler etc. This method will prevent, for example, a showcase model being dismantled before testing can take place.