What does the current US boiler code, and for that matter British and Australian as well, say about using vintage cast iron steam turrets? If outlawed, what is an acceptable replacement? New cast iron, cast steel, welded steel, bronze...?

We have a steam turret we are looking at replacing, so facts and actual practice will help with the discussion and decisions process

This seems like a straight forward question that should have a straight forward answer, but as with many things it gets a little convoluted. There are two predominate documents used throughout the US as "boiler codes". First, the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code which deals exclusively with new construction and second, the National Board Inspection Code (NBIC) which deals with boiler and pressure vessel installation, inspection and repair/alteration. Depending on the situation one or both Codes might be utilized.

Let's start with a newly constructed boiler where an old turret valve is to be used. ASME Section I, Rules for the Construction of Power Boilers sets a boundary around a complete boiler system. Any component in the system that falls within the boundary must be manufactured and assembled by an ASME Certificate holder including mechanically assembled piping. For a locomotive boiler the boundary, called "Code jurisdictional limits" in the text, is the boiler itself and any piping or appurtenance attached to the boiler up to and including the first valve. In the case of the old turret, if there is a new intervening valve between the boiler and the turret, then the turret falls outside the Code boundary so is not excluded from use by the ASME Code. If the turret is the type with an integral isolation valve, then the entire turret is subject to the requirements of the ASME Code and may not be used.

Where you have an existing boiler with an existing turret, the organization that regulates the industry the boiler operates in may have some rules, but it is essentially up to owner/user to determine if the component and application are safe. The NBIC does have some recommended practices for inspection.

Perhaps the most important thing to remember is the regulatory organization who's jurisdiction the boiler operates in has the ultimate say and they may be more or less restrictive than the Codes.

The document you might want to reference is the ASME B31.3 process piping guide which takes over where ASME section 1 ends.

For clarification: I understand this question to apply not to an old appliance being used on a new boiler, but on the continued 'safe' use of a cast-iron piece applied to an old boiler (possibly grandfathered).

Specifically, what are current NBIC (and British/Australian) regulations on cast-iron turrets or manifolds being used on existing boilers (presumably NOT with any cast conctruction details!)

Reading between the lines ... he may be asking if it is wise to continue using a cast-iron turret in his particular application. Does that involve the application not being above a specific size, or steam-generation capability, or range of pressure? I'm presuming he has in fact done NDT testing of an appropriate kind and there are no known or observed flaws in the structure...

Australia says a lot about compliance with AS 1271 in terms of what's generally required for all old valves ( in the BOILER MOUNTINGS section), but also has a small paragraph specifically pertaining to main turret valves. They like a dye penetrant NDE as well as a thorough visual examination, as well as a hydro test either in place at 125% or separate at 150%. The turret valve section calls out no more than 3 MM of wear permitted in seats, and particular attention to the neck of any flange attached valves. So, anybody have AS 1271?

The turret in particular is a cast iron turret built to a Henschel standard design from 1907. It has no ability to shut off the steam supply from the boiler flange, and is built so the safety valves are connected to the boiler through the same boiler connection as the turret. We are currently sending it away to a company to do NDE dye testing and then pressure testing with water.

I am mostly looking for info on the use of old cast iron turrets being illegal, due to their age or construction. If not illegal, than any considerations we should take into account when using it!

It is indeed an old turret on an old boiler

The NDT that is being performed is an excellent ides. I would like to caution you to NOT have it X-rayed as X-rays of cast iron always look bad.

Nothing I have read suggests that if they were well designed and compliant at build and maintained and proven to be in good condition they would be illegal either in Australia or the US. Lots of them are still in service and going strong. No idea about Denmark.

The answers so far are very informative. I am going to try to go a bit deeper here.

The ASME does allow the use of Cast Iron parts in low pressure use. This is also true with the EU standards. Low pressure would be under 15 psi. Heating boilers or small boilers that have radiator type sections that are pressed together can be cast iron or cast steel.

I would have your turret subjected to material analysis to see if it is really cast iron or if it really is cast steel. Often we confuse the two. It was not uncommon for these items to be cast steel....but called "cast iron."

We have made turrets like this as fabrications. In fact, we have made super heater headers, turrets, pipe flanges and all sorts of things that once were "cast" items, but that are now more economical to fabricate. The drawing shown would not be a difficult weldment to produce. It is a few flanges, some pipe and a few other shapes, all of which can be designed using Sections I/IX of the ASME code and using materials found in Section II.

Consider reverse engineering the turret. Paul mentions in short and I am trying to emphasize; it really is up to the jurisdiction if they want to accept it or turn it down. I can give you 5 examples in the US where they are accepted and rejected (which is why we have fabricated these items). You could have a UT study done and determine by methods of reverse engineering if the turret is still "sound" however, I would check with your jurisdiction to see if they will accept the results if shown to be favorable. No use spending money to reverse engineer if in the end the jurisdiction says..."Cast Iron...NO WAY...." Jurisdiction could say things like...."we will accept if it makes a margin of safety of 6." Or, "We will allow two more annual inspections with the item and it needs to be replaced." Or, "We simply are not allowing such items to remain in service."

Please keep in mind, even if it is in the "code", a jurisdiction can enforce special rules or regulations BEYOND those of the code. This is why this can easily be a case by case basis item.

Kindly,

There are 2 boundaries defined by ASME Section I Power Boilers. The first is the "boiler proper" which is the pressure boundary up to the first nozzle. This is certified by the Certification of Shop Compliance and Inspection on the ASME P-2 Form. Plug the blow downs, feed water nozzles, safety valve holes, washouts, etc, blank the dry pipe hole and conduct the 1.5 MAWP hydro and sign off the boiler itself.

All the Boiler External Piping, from the boiler nozzles to the limits of the BEP are supposed to be certified by an ASME "S" or "A" Stamp holder and documented by executing the Certification of Field Assembly and Inspection portion of the ASME P-2 form.

I have never seen a Field Assembly executed on a locomotive P-2 form. Some Jurisdictions do not enforce this for small boilers (less than 200 BHP). From a practical stand point, even if the piping is threaded together by a pipefitter, what extra safety is accomplished by mobilizing an "A" Stamp holder with Authorized Inspector to witness a hydro and sign a form at a cost of $3K+? Especially if the boiler is the size of a 55 gallon drum, has no tubes, costs only $8K and feeds a dry cleaner...
Most AIs that never inspected a locomotive boiler before probably never saw a steam injector either. Your Chief Inspector may vary.

I believe the relevant section of Australian code AS-1271 (2003) is on scribd at

https://www.scribd.com/doc/94245048/As-1271-2003-Safety-Valves-Other-Valves-Liquid-Level-Gauges-and-Other-Fittings-for-Boilers-and-Unfired-Pressu

I think I have a PDF of the 1997 version if someone wants a copy.

Thanks for all the interesting replies to this good question, if you don't mind a bit of topic drift. How does the typical throttle valve, J-pipe, and dry pipe fit into this? I would assume that most "new" replacement boilers will reuse the valve casting and J-pipe from the original boiler. Considering that it would be possible to perform an initial hydrostatic test and inspection without these components in place, are they typically considered to be within the "code jurisdictional limits"? It must be a highly unusual situation for the modern boiler designer and inspector to find one with a "main stop" situated inside the pressure vessel! In the case of entirely new build locomotives under ASME code (O'Connor, Kloke) has a traditional doublebeat throttle valve been used?

Thank you; Pat Hosford

Pat,

You have asked some excellent questions on a topic that generated some spirited debate during the creation of Part PL, Requirements for Locomotive Boilers in Section I of the ASME Code. A little history: The initial plan to deal with the use of existing parts such as throttle valves, super heater headers, turrets and other appurtenances was to develop a method to analyze the component's current condition and certify the component for the service it would be in. This was a non starter with the main ASME Committees as the Code does not allow the use of used material in new construction. The next suggestion was to require all components within the Code Jurisdictional Limits to be manufactured new. This idea has some potentially huge economic consequences. Say your locomotive has a super heater header with integral front end throttle, the existing part is in perfectly serviceable condition, but under the rules of the Code you have to replace it. The cost of recreating such a complex component would be staggering and would not necessarily improve the safety of the boiler system. The compromise was to create a new Data Report that can be used as both a master, certifying the entire boiler system or as a partial, certifying only the part documented on the report.

If a locomotive boiler owner/user wanted or needed to replace a throttle valve, they could without having a Code certified shop build the part. When you buy a bronze globe valve with a WSP (working steam pressure) rating, the valve was probably not manufactured by a Code certified shop. The Code acknowledges that valve manufacturers know what they are doing and can self certify their products for the service they were designed for. In some cases, the Code requires valves to be manufactured per the requirements of ASME B16.34, Valves - Flanged, Threaded and Welding End. There is no manufacturer's certificate for B16.34 so anybody can buy a copy and design a valve to the requirements. I know of a couple of newly constructed poppet style dome throttles that were manufactured this way.

While the throttle valve does not need to be manufactured by a Code certified shop, in a new construction environment a Code certified shop must take responsibility for the installation and document it on the appropriate Data Report form. This is true of any mechanically assembled piping within the Code Jurisdictional Limits and, again, only for new construction.

Paul

Thanks so much for the great information Paul.
Pat