In the 2009 Addenda to Section I of its boiler code, ASME introduced Paragraph PFT-52 which includes a mandatory requirement regarding the use of fusible plugs on hand-fired boilers. I believe that this is the ASME Code’s first mandatory requirement for fusible plugs in its 95 year history.

In August, 2010, the ASME BPV Subcommittee on Safety Valve Requirements will be considering reinstating the four percent limit on the blowdown of safety valves that are installed on hand-fired boilers. The four percent limit was in place from 1914 until the late 1990s.

I am aware that most locomotives are not affected by the ASME code, and that many don’t have fusible plugs.

Bruce E. Babcock

"Hand Fired" boilers would mean boilers without automated firing apparatus of any fuel type, whether stationary or portable? To clairify, this would mean that new hand fired boilers (such as for traction engines or locomotives) would be required to have fusible plugs?

Also, at this time, NBIC standards have not changed, correct?

With regards to the 4 percent saftey valve: would this be equivalent to the "old style" safety that seats within 5 pounds of rated pressure? If so, this actually might be looked upon very favorably by many.

Michael Seitz
Missoula MT

Does anyone know a source for 1/2" NPS water-side fuse plugs? Eugene Ernst only has 1".

Thank you,

S.O.

Stan,
These folks list a 1/2" plug.
http://www.boilersupplies.com/fusible-p ... fault.html

^^^Thank you Mike, but that's a fire side plug. Still, good to know I can get a 1/2" fire side plug if I need one.

S.O.

It will be interesting to see how some Jurisdictions react to this new rule. There are a lot of manually fired boilers on locomotives, tractors, steam launches and in stationary service without fusible plugs. I can hear the question in my mind, "If the ASME believes that there is a compelling argument that prior to PFT-52 manually fired boilers without fusible plugs were unsafe, then fusible plugs should be required on all existing boilers as well." I am curious, was there a rash of failures due to low water on manually fired boilers prior to this?

S.O.

I know those locomotives under FRA jurisdiction are required to have fusible plugs.

No, they are not, but you are required to note if it has one or not.

IMHO I don't care for fusable plugs, as they can be unreliable, are prone to leakage, can lead to more maintenance, and there is no compelling reason for a competant operator to let himself get into a situation where he needs it. I also think that it leads to a false sense of security in some circles. Diligent boiler care and operation is the only failsafe for boiler operation.

Case well stated.

Hear, hear! -S.O.

PFT-52 has been eliminated from the 2013 edition of the ASME Code. Fusible plugs are no longer mandatory on hand fired boilers.

As a side note, ASME is the code that covers construction of new vessels; NBIC is the code that covers inspection, maintenance and repair of vessels once put into service. Two different animals.
mld