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Boilers

The Gauge 3 Society allows builders to opt for the "3 bar-litre" specification which does not require testing but is not really practical on larger locomotives. This would mean the volume of the boiler in litres multiplied by the pressure of the steam in bar, should not exceed 3. Thus a 3 litre boiler giving steam at 1 bar (14.5 psi) is the same as a 0.5 litre boiler giving steam at 6 bar (87 psi). It is permissible to run your own steam loco untested on your own track or for testing and examination with testers present. BUT at a "Get To Gether" or on other members tracks a Boiler Certificate will be required. There are several boiler testers around. The G3S will accept current MES, NAME or Southern Fed. Certificates.

A case in point would be my own loco which is designed to fulfill two functions. One as a G3 loco and the other as a N2.5GA loco. The boiler although below the 3BAR/Litre limit for a G3S loco, (it will run at 4BAR and is 700ml in this mode), it needs certifying to 6BAR for its role as a N2.5GA loco. Thus it will be certified as a N2.5GA loco.

Further reading.

Model Boilers and Boiler Making. K.N. Harris
Soldering and Brazing. Tubal Cain
Model Locomotive Boilers: Their Design and Construction. Martin Evans
Model Locomotive and Marine Boilers. Martin Evans

NOTE

The Gauge '3' Society is a member of the "Southern Fed." group of clubs. The 2018 Guide used in boiler examination is called "The Orange Book", This was updated in November of 2017. All boilers should be made from Copper only, although rivets, silver solder, brazing and TIG welding is acceptable. The practice of caulking older boilers with soft solder is at the discretion of the boiler tester -whose ruling is final. No Brass is allowed in the cold water circuit, but Bronze is acceptable. Brass is allowed in the steam circuit provided it is non condensing. There should be TWO different means of filling the boiler with water whilst in steam such as; a manual tender pump, an axle pump, or a steam injector. The water gauge MUST have a blow down valve at the base of it.

The Valid Boiler Certificate MUST be shown to the person running the GTG before the locomotive is allowed on the tracks. The Host will make a note of it in the Guest Book.

You may be asked for a Valid Gas Tank Certificate if the loco uses Propane or Butane gas. Locos running from disposable gas canisters are deferred as the canister is seen as local fitting.


This is unfortunately horribly written in Legalese rather than written in English, but it is however required reading for those with a steam boiler...

CE Marking of Boilers.

For the purposes of this document, it is considered the term "working pressure" to have the same meaning as maximum allowable pressure in PSSR and PER. The following tables outline the requirements of PER that a manufacturer making pressure equipment in the course of business would need to meet for the documentation, design, and manufacture of boilers likely to be used by the model engineer. Steam boilers are classified according to pressure, volume, or a combination of both.

1 bar = 14.5038 psi

1 litre = 1.760 pints

1 pint = 0.568 litre

10 psi = 0.689 bar


Table 1

LESS THAN 0.5 BAR OPERATING PRESSURE (No upper volume limit)

Below 0.5 bar (approx. 7.25 psi) PER is not applicable. However, the boiler and any ancillary equipment (if supplied) must comply with the requirements of PSSR in matters relating to design and construction.

The pressure system or article shall be properly designed and properly constructed from suitable material so as to prevent danger -PSSR Regulation 4.(2)
The pressure system should be provided with such protective devices as may be necessary for preventing danger -PSSR Regulation 4.(5)

Pressure Vessel Only:

The boiler shall be permanently marked to show the manufacturers identity and its serial number.

Documentation should include:

The manufacturers name and address.
The date of manufacture.
The maximum allowable pressure (i.e. 0.5 bar).
The minimum allowable pressure, if other than atmospheric.
(A vessel of such a low operating pressure could be part of a condensing system and therefore subjected to a vacuum).
Design temperature.
Valid pressure test certificate.
Operating instructions.
The standard to which the vessel was built.

Additionally:

Provision should be made to allow the fitting of protective devices, (e.g. a safety valve, a pressure gauge, and , if a heated vessel, provision for fitting a device to assess the water level). Provision should be made to allow the boiler to be drained.

Kit:

In addition to the above the fitting should be supplied, and if a heated vessel, a means of being able to remove or shut down the heat source in an emergency should also be provided.

Completed Model:

In addition to the above, the fittings should be installed with the safety valve pressure set and tested. The boiler test certificate should be suitably amended to record this fact. The manufacturer should be able to provide sufficient written information regarding design and construction as may be reasonably foreseeably be needed to enable the provision of the Regulations to be complied with. The manufacturer doesn't necessarily have to supply such information to the purchaser, but it must be retained for inspection should the need arise.


Table 2

BOILERS UP TO AND INCLUDING 2 LITRES VOLUME.(No upper pressure limit)

Boilers in this category need to have been designed and manufactured in accordance with "Sound Engineering Practice" (SEP) in a member state in order to ensure safe use.

Pressure Vessel only:

The boiler should be marked to show the manufacturers identity and its serial number. CE marking shall not be affixed to SEP equipment.

Documentation should include:

The manufacturers name and address.
The date of manufacture.
The maximum allowable pressure.
The volume of the boiler.
Valid pressure test certificate.
Intended use.
Instructions for use.
Weight (empty).

Additionally:

Provision should be made to allow the fitting of protective devices, (e.g. a safety valve, a pressure gauge, and , if a heated vessel, provision for fitting a device to assess the water level). Provision should be made to allow the boiler to be drained.

Kit:

In addition to the above the fitting should be supplied, and if a heated vessel, a means of being able to remove or shut down the heat source in an emergency should also be provided.

Completed Model:

In addition to the above, the fittings should be installed with the safety valve pressure set and tested. The boiler test certificate should be suitably amended to record this fact.

The manufacturer needs to be able to show the boiler has been designed and manufactured in accordance with "Sound Engineering Practice". Copies of all drawings should be retained in order for subsequent inspection by the relevant authorities should the need arise. The manufacturer doesn't necessarily have to supply such information to the purchaser.


Table 3

CATEGORY 1 (Boilers above 2 litres volume, up to and including 50 bar-litres, maximum pressure 32 bar).

Boilers in this category need to have been manufactured in accordance with Module A of the Conformity Assessment Procedures (Internal Production Control).

What to expect:

Pressure Vessel only:

The boiler shall be permanently marked to show the manufacturers identity, its serial number, and the CE mark.

Documentation should include:

The manufacturers name and address.
The date of manufacture.
The maximum allowable pressure.
The volume of the boiler.Valid pressure test certificate.
Intended use.
Instructions for use.
Weight (empty).
A Declaration of Conformity, that the equipment satisfies the requirements of the Pressure Equipment Directive.
Boilers should have the appropriate material certificates.

Additionally:

Provision should be made to allow the fitting of protective devices, (e.g. a safety valve, a pressure gauge, and , if a heated vessel, provision for fitting a device to assess the water level).
Provision should be made to allow the boiler to be drained.

Kits and Completed Models:

As Table 2.

The manufacturer will have drawn up technical documentation for the equipment that includes manufacturing drawings, design calculations, examinations carried out, test reports etc. along with a Declaration of Conformity. Records of materials used in manufacture shall be kept . The manufacturer must keep documentation , for inspection by the relevant national authorities, for a period of 10 years from the date of manufacture. A method in internal production control must be established that ensures the manufacturing process enables the manufactured pressure equipment to comply with the technical documentation and comply with the requirements of the Directive. All the relevant Essential Safety Requirements must be met.


The national organizations that administer the affairs of various branches of the hobby have somewhat more stringent requirements in that whenever steel is used in the construction of a boiler, irrespective of the volume or working pressure, full traceability of materials are required and the boiler should be marked with the relevant material codes. Any joining of a steel boiler will have been carried out by a competent welder.

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Page last modified on January 20, 2018, at 11:30 AM