Safety and Relief Valves

[cyberbadger]

There is a difference between a Safety Valve(SV) and a Relief Valve(RV) - but sometimes they are muddled in conversation and also considered the same in certain jurisdictions(Countries, States, Provinces, etc).

Things gets more complicated because of the different types of valves.

Things get still more complicated because of the different engineering codes, laws, and insurance in different jurisdictions(Countries, States, Provinces, etc) that dictate what is required, what is allowed, and what is not allowed.

Things get even more complicated because of the intended use - Steam boat/launch, Traction Engine, Locomotive, Stationary Commercial/Industrial, etc, etc --- Luckily we can limit this discussion to Steam boats/launches (Non Commercial).

A good primer:
http://en.wikipedia.org/wiki/Safety_valve

In the USA, the ASME and the ASME approved/certified Safety Valve manufacturers have been turning away for decades from hand fired boilers -- It's a very small slice of the pie. So much so that small ASME Safety Valves are considered almost as one time use only!!! (Including Kunkle)

Two threads on smokstak (Primarily USA traction engine folks) regarding this:
http://www.smokstak.com/forum/showthread.php?t=40090
http://www.smokstak.com/forum/showthread.php?t=99521

I personally like the more progressive valves then the pop of valves.

What safety and/or relief valves do you use on your steam launch?
How many?
Brand(s)?
Engineering Standard/Code?

Please Include your Country/State/Province when you reply.....

I'm in Ohio, USA - But I also plan to take my launch to NY, USA.
My new ASME boiler will have a new ASME Kunkle Safety Valve.

-CB

[cyberbadger]

A more direct question...

I bought this new direct spring (more progressive, not pop) valve from a company in the UK.
(The bottom part is a BSP to NPT pipe adapter I bought)

I tried it on my current boiler that has 125MAWP as a secondary under steam and was pleased with it's characteristics not being a pop off.

I'm planning on using it as a secondary valve on my new 200MAWP ASME code boiler. It would set it below the 200PSI set ASME code steam pop of valve made by Kunkle.

It's body reads ATAM 15mm and has it was stamped/punched with "Tested 300LBS". It has a hologram ATAM Sticker with Original on the body, not sure how long that will be able to stay there .

Any thoughts on having this as a secondary safety/relief valve?

Again I'm in Ohio, USA - hopefully want to steam in New York State, USA eventually....

-CB

[fredrosse]

Remember to test the ASME Code safety valve at least annually, many people will test their ASME Code valves more frequently. Testing the ASME Code valve, and having it set by a certified shop if it is too far off its setting is a code requirement.

Having an extra relief valve with a lower setting is not a code requirement, and having that extra valve would require gagging the non-code relief valve which has a lower setting in order to test the code valve.

In a previous post on this thread, you stated ...."In the USA, the ASME and the ASME approved/certified Safety Valve manufacturers have been turning away for decades from hand fired boilers -- It's a very small slice of the pie. So much so that small ASME Safety Valves are considered almost as one time use only!!! (Including Kunkle)"

I have never heard that these valves might be considered "one time use", where did you get that impression?

[cyberbadger]

In a previous post on this thread, you stated ...."In the USA, the ASME and the ASME approved/certified Safety Valve manufacturers have been turning away for decades from hand fired boilers -- It's a very small slice of the pie. So much so that small ASME Safety Valves are considered almost as one time use only!!! (Including Kunkle)"

I have never heard that these valves might be considered "one time use", where did you get that impression?

Look at the smokstak links in the first post on this thread (State Inspectors have commented in those posts).

The went from conical seats to flat seats. The flat seats don't always reseat properly and are not meant for frequent use.

Testing the ASME Code valve, and having it set by a certified shop if it is too far off its setting is a code requirement.

Many shops in the US will charge the same price or above what a new valve would cost to recalibrate it for small boiler. (Not worth their time)
Again - Look at the smokstak links in the first post on this thread.

-CB

[DetroiTug]

That wasn't a state inspector that wrote this:

"IF VALVE IS EVER ACTIVATED, IT SHOULD BE REPLACED." .

The only type of relief valve I've ever read and heard this about is a home hot water heater. Entirely different valve and application.

Kunkle offers different types of seats for various service requirements of power boilers. Teflon for increased cycling, per their documentation.

-Ron

[cyberbadger]

That wasn't a state inspector that wrote this:

"IF VALVE IS EVER ACTIVATED, IT SHOULD BE REPLACED." .

You are correct DetroiTug/Ron.

But a state inspector wrote this:

If your valve is a bevel seat valve, keep it. They aren't made any more, and for hand fired boilers they are better than the new flat seat valves.

And the state inspector also wrote this:

Buy the new code valve. Yes, there is a chance it will open at somewhat other than the pressure stamped, but it WILL open. It is correct that most valve rebuilders won't work on the smaller valves, or charge high dollars for doing so. The reason is that the smaller valves (less than 2") are throw-away valves. The rebuilders are making their living fixing the larger than 2" valves that are cheaper to rebuild than replace. The pricing mentioned here is peanuts in the "real" world. When you start spending thou$ands of dollars, then valve shops will listen.

Kunkle offers different types of seats for various service requirements of power boilers. Teflon for increased cycling, per their documentation.

They do offer the teflon seats but they can become problematic because they tend to start conforming(changing shape) to the seat, and can start to leak because of the conforming.

Tell me were I can buy a new 1/2" remote discharge ASME code Section I steam safety valve for less 500lbs steam/hour at pop off at 200 PSIG for less then $300 and I'll dance you a jig. I'll give you a high five if you can find one at all...

-CB

[DetroiTug]

Start dancing

http://www.mcmaster.com/#steam-relief-valves/=ujbf26

6187T17 These are Kunkle brand, just bought one.

$178

I read all the assertions that the bevel seats are better etc. My guess the reason as to why they got away from the bevel seat, while sealing well, once worn and the tapers deformed they had a higher probability of sticking shut. i.e. taper shank tooling. Given the choice between not opening and leaking slightly they chose reliable opening and possibility of a small leak over not opening at all.

-Ron

[cyberbadger]

DetroiTug,

Can't dance, they are more then 2X the flow capacity. At 200 PSI set it's: 1,206 lbs steam/hr. They have the a link to the chart on that mcmaster carr page. That's part of what I was getting at - ASME valve manufacturers/shops don't really cater to the small boiler crowd - not worth their time.

That's where I bought the one Kunkle for my first boiler that once stuck shut 10-15 PSI above the setpoint before a tap made it pop, but I chose the Heavy Duty model(Brass seat) instead of the Extended-Life model(EPR ethylene propylene seat) that you did.

-CB

[DetroiTug]

Kunkle states they test and calibrate each valve before it is shipped. I've been around a lot of steam plants and have never seen or heard of a new relief valve that far out of calibration. I read some of the other claims about valves not calibrated properly from the factory, my guess is the pressure gauges are inaccurate. I run a Westinghouse test gauge and the blow off set pressure is 100 psi and it opens right at 100 psi on the gauge.

The steam car is the same way, a kunkle purchased from mcmaster carr opens right at 250 on the gauge exactly as it should. That is an original Locomobile gauge 114 years old.

-Ron

[cyberbadger]

DetroiTug/Ron,

The one I have pops correctly except for that one time where it needed a tap.
Personally I like to run my boiler with one antique, and one new, for checking purposes but also so I can read it from different angles.

-CB