Dismantling Joint vs FCA 2

[jacky89]

When do you ever need to use a dismantling joint? I always use flange coupling adapters at locations where something needs to be disassembled such as at valves and flow meters.

 

[bimr]

Dismantling joints are used for dismantling the equipment fitted in the pipe line. Dismantling joints are used before butterfly valves, pumps and other equipment to provide flexibility to the equipment installations by joining flanged spigot and flanged coupling adapter into one assembly.

Dismantling joint consist of double flanged fittings that allows for longitudinal adjustment in flanged pipe systems. Dismantling joints are capable of accommodating up to 2" in longitudinal adjustment depending on diameter. The adjustability is provided by the telescopic action of the flanged spigot within the flange adaptor. The dismantling joint can be locked at that length with the tie bars supplied. Longitudinal adjustment of this magnitude allows for fast and simple maintenance of valves, pumps etc. and simplifies future pipework modifications, with reduced down time and simplifying the method of anchoring the pipe system.

 

[jacky89]

I understand what the dismantling joint does. But I've been using FCAs for the exact reasons you listed for dismantling joints and had no issues. I'm just wondering under what circumstances will FCA not be able to accomplish what the dismantling joint can accomplish.

 

[rconner]

I have noticed at the site

http://www.ejprescott.com/media/reference/FlangeAdaptorsB-22.pdf

the statement regarding dismantling joints under the heading, "Working pressure",

"All Dismantling Joints are fully end load resistant and have a pressure rating equal to that of the flange...",

whereas I don't happen to see a comparable statement under the subsquent text regarding at least one type of different flanged coupling adapter(FCA) available from the same vendor (you will see also at least the latter FCA structure does not offering the same endwises field adjustment/adaptability, nor flexibilty, of the dismantling joint pictured). While I suspect the dismantling joint may well demand some higher price and best tailored to more demanding circumstances that really require same, you may read into these observations, and an actual look at some comparative designs depicted, what you will.

 

[chocobo1198]

Flanged coupling adaptors do not provide longitudinal restraint. Well, unless you guys are talking about restrained flanged coupling adaptors. In this case, you would have been using RFCA rather than FCA in the discussion... I don't use RFCAs because it bites onto the pipe and damages the pipe coating. I use M11s and modified versions of the M11s for restraint when using FCAs or couplings. Dismantling joints provide the flexibility and are restrained. I don't know what sizes these are available in though. I've worked on pipe ranging from 8" to 72" and have never used dismantling joints except in PRV stations and in bypass piping applications.