What are Dismantling joints and uses

Dismantling joints are essential components of a pipeline. When it becomes necessary to repair or replace critical elements in the pipeline, such as valves, water meters, flow meters, and others, a gap needs to be created between the flange of these elements and the pipeline. In such cases, dismantling joints are required as they are a unique product designed specifically to facilitate the creation of this gap. This gap is created by adjusting the length of the dismantling joint.

Disai Product Page

Dismantling joints consist of a protruding flange and a flange adapter. When the protruding flange moves towards the flange adapter, the length of the protruding flange enters inside the flange adapter, and the length of the joint becomes shorter. When the protruding flange moves in the opposite direction of the flange adapter, the length of the protruding flange exits the flange adapter, and the length of the joint becomes longer.

Coating material for dismantling joints:

For natural fluids such as water, oil, and gas at room temperature, a regular FBE coating is suitable. Corrosive or high-temperature chemicals require special surface treatments. For seawater, the interior can be lined with epoxy, and the exterior should be coated with corrosion-resistant coating or with epoxy glass flake coating on both the inside and outside. Strongly acidic fluids, corrosion-resistant nylon type 11 is the best choice. For fluids with temperatures exceeding 100 degrees Celsius, heat-resistant epoxy powder should be used. For pipelines with high contamination, an abrasion-resistant polyurethane inner lining should be used.

Material used for manufacturing dismantling joints:

If the working pressure rating of your pipeline is &#; 25 bars, a ductile iron joint is the preferred choice due to its wide versatility, corrosion resistance, and competitive price. However, if the working pressure rating is &#; 40 bars, you should choose a steel joint to withstand the high pressure. The steel material can be carbon steel, stainless steel, or other steel alloys.

Importance of using dismantling joints

The use of dismantling joints plays a crucial role in the design and implementation of pipeline systems that involve valves, pumps, and measuring meters. These double-flanged pipes allow for the necessary longitudinal adjustment. It can be secured at the desired length using the provided tie bars.

The purpose of using dismantling joints is to facilitate the installation and removal of pipeline valves and components. These joints provide the longitudinal adjustment, making it possible to insert the valve into the desired section of the pipe.

This adjustment also assists in properly aligning the valve next to the joint. That can be adjusted to the appropriate length before securely connecting it to the flanges. The reverse sequence is used for the dismantling process, as readjusting the length of the dismantling joint provides enough space for loosening and removing the valve.

In both cases, dismantling joints ensures quick installation and dismantling, ultimately increasing efficiency and reducing downtime. The procedure is carried out in the same way as connecting pipe sections together. Some dismantling joints can also be used without imposing constraints on flexible pipeline systems.

Furthermore, dismantling joints can also be useful in filling gaps. For example, when installing a pump in a permanent location, it needs to be connected to a pipe protruding from the wall.

The basic design principle of these joints:

There may be various versions of dismantling joints available to suit different applications. But the fundamental design principle for all of them is the same, which includes:

• A flange adapter on one side of the joint is securely connected to the pump or valve using a flange.
• The F-piece or the central flange known as the pivotal flange on the other detachable end of the joint to connect in the opposite direction, also pushed into the flange adapter.
• To install or remove valves with longitudinal adjustment up to ±25mm, these two components can be pushed towards each other until the detachable joint is secured between the pipe parts or the valve and the pipe.
• Provided tie bars are used to restrain and connect the flanges for appropriate use of the dismantling joints. At the same time, they also assist in transferring the force occurring on one side of the joint to the other side.

Dismantling joint on pump suction

Dismantling joint on pump suction

Bahman07

(Mechanical)

(OP)

24 Feb 21 06:08

Hi
I am new here, and this is my first activity.
I am working on a water pump station. there is a debate on using dismantling joint on pump suction pipe for maintenance. Since we are using expansion joint on this line, is there a way to not considering dismantling joint? I have to say that suction pipe is from a concrete tank to pump nozzle.
Basically, are there any standards or practices for mandatory using of dismantling joint?
Thanks in advance

Replies continue below

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RE: Dismantling joint on pump suction

bimr

(Civil/Environmental)

24 Feb 21 16:21

You need to supply a little more information. Is this for a 5 HP pump or a HP pump? Is the pipe 12-Inches or 50 feet long? What type of pipe?

There are no standards for using dismantling joints.

RE: Dismantling joint on pump suction

LittleInch

(Petroleum)

24 Feb 21 16:40

It may be common terminology in your workplace, but it isn't in mine.

Also what type of expansion joint - there are many types available.

A drawing or sketch would help a lot.

There's noting mandatory, but if you need to remove the pump and you can't slide the pump back a few mm to remove a spool piece then you can get into lots of trouble trying to generate enough movement to break the pipe joint.

What is a "dismantling joint".It may be common terminology in your workplace, but it isn't in mine.Also what type of expansion joint - there are many types available.A drawing or sketch would help a lot.There's noting mandatory, but if you need to remove the pump and you can't slide the pump back a few mm to remove a spool piece then you can get into lots of trouble trying to generate enough movement to break the pipe joint.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Dismantling joint on pump suction

Bahman07

(Mechanical)

(OP)

25 Feb 21 21:54
In order to more detail, I could not find the HP of pump, it is 355KW. The suction pipe is 24" reducing to 20". Length of pipe from tank to pump is 10m. Pipe material is carbon steel.
I attach an image of component which I mean.
Our expansion joint has not been finalized yet, but it is preferably rubber single type, and it connected to pump nozzle.


DISMANTLING JOINT:

HiIn order to more detail, I could not find the HP of pump, it is 355KW. The suction pipe is 24" reducing to 20". Length of pipe from tank to pump is 10m. Pipe material is carbon steel.I attach an image of component which I mean.Our expansion joint has not been finalized yet, but it is preferably rubber single type, and it connected to pump nozzle.DISMANTLING JOINT:

RE: Dismantling joint on pump suction

TugboatEng

(Marine/Ocean)

25 Feb 21 22:30

Bahman, in this case it depends on who installed it. Personally, I put double gaskets in during the fabrication phase. This ensures that the joint will not be in compression when installed. This allows the joint to be slid in and out of position easily or if the equipment is installed between two joints it can be slid in and out of position. In the field, I find this to not be the case and usually sections of piping have to be removed for access.

RE: Dismantling joint on pump suction

Artisi

(Mechanical)

25 Feb 21 23:36

A joint as such connected to a pump suction is very likely to cause poor inlet conditions leading flow separation and vibration.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

RE: Dismantling joint on pump suction

bimr

(Civil/Environmental)

26 Feb 21 02:40

Most pumps require a straight run of 5 pipe diameters before the pump suction. That would be about 10 feet.

Dismantling joints are used where it will be difficult to remove the piping because of clearance limitations. If you are routing the pipe straight from the wall to the pump, you will have problems removing the suction pipe at a later time.

I would recommend that you skip the expansion joint and just use the dismantling joint. Many piping designers avoid using expansion joints. Design the pump piping so there is no expansion joint. Expansion joints are not reliable, prone to fatigue failure and thus cause loss of production and could possibly injure operators and maintenance workers.

Install the dismantling joint at least 10 feet away from the pump suction. As you stated, you have 10 meters to work with.

Be sure to use an eccentric reducer to avoid trapping air.

RE: Dismantling joint on pump suction

TugboatEng

(Marine/Ocean)

26 Feb 21 03:26

I strongly disagree agree with expansion joints being prone to failure. Incorrect material selection and pipe support cause issues that are not the fault of the joint itself. Oil is tricky because compatible materials are expensive. But for water, neoprene, EPDM, and silicone, can all provide 30+ years of trouble free service if correctly applied based on temperature.

RE: Dismantling joint on pump suction

2

bimr

(Civil/Environmental)

26 Feb 21 03:59 THE DIRTY LITTLE SECRETS OF PREMATURE EXPANSION JOINT FAILURES

How to Troubleshoot Expansion Joint Failures

a last resort due to their construction they are a weak point in the piping system

Both rubber and metallic expansion joints can and will fail. The best insurance against a catastrophic expansion joint leak is don't use expansion joints.

As I said, an exp joint is always the LAST resort.

RE: Dismantling joint on pump suction

TugboatEng

(Marine/Ocean)

26 Feb 21 04:46

Bimr, your first post confirms what I said about improper installation. You're other posts are in reference to high temperature high pressure applications where pipe design including expansion loops is used to limit strains. Those are niche applications.

RE: Dismantling joint on pump suction

HTURKAK

(Structural)

26 Feb 21 07:12

- The use of fixable dismantling joint will be necessary if the pump can not installed again if dismantled for any reason. That is, if the pump inlet and outlet piping has axial thrust to pump , and the outlet piping is connected to header , you cannot install the pump if you do not dismantle the total outlet piping. You should question that, Can each pump be dismantled and installed separately ? if yes you do not need dismantling joint..

- The use of expansion joint: Is this recommended by the pump manufacturer ? . If not, i want to remind that, in case of expansion joints at suction and pressure side, the pump casing, frame..will experience the full thrust.. That is, you are expected to ask manufacturer's permission!!!

I suppose that the pumps are omega type centrifugal pumps similar to the picture below;




If you provide more details , ( at least some sketches for proposed piping etc). you may get better responds..

Dear Bahman07 (Mechanical),- The use of fixable dismantling joint will be necessary if the pump can not installed again if dismantled for any reason. That is, if the pump inlet and outlet piping has axial thrust to pump , and the outlet piping is connected to header , you cannot install the pump if you do not dismantle the total outlet piping. You should question that, Can each pump be dismantled and installed separately ? if yes you do not need dismantling joint..- The use of expansion joint: Is this recommended by the pump manufacturer ? . If not, i want to remind that, in case of expansion joints at suction and pressure side, the pump casing, frame..will experience the full thrust..I suppose that the pumps are omega type centrifugal pumps similar to the picture below;If you provide more details , ( at least some sketches for proposed piping etc). you may get better responds..

RE: Dismantling joint on pump suction

Bahman07

(Mechanical)

(OP)

Additional reading:
International Standards for Gate Valves: ANSI vs. API Explained

Contact us to discuss your requirements of Dismantling Joint Manufacturer. Our experienced sales team can help you identify the options that best suit your needs.

27 Feb 21 07:26
I attached an image of my 3D model. Suction is the straight line to pump, and the dimension is in mm.
We have the permission of using Expansion joint.

HI HTURKAKI attached an image of my 3D model. Suction is the straight line to pump, and the dimension is in mm.We have the permission of using Expansion joint.

RE: Dismantling joint on pump suction

HTURKAK

(Structural)

27 Feb 21 11:01

Hi Bahman07 ,

Can you provide the isometric dwg of piping showing the supports , valves fittings etc..?

My suggestions will be,

- for the suction side; provide fixable dismantling joint but not expansion joint. The reducer shall be ecc. reducer with flat on top construction. Provide supports to keep self standing the inlet piping .

- For pressure side , you should provide C.V. , Check Valve , and may be by-pass valve.. You do not need neither expansion joint nor fixable dismantling joint for the pressure side. Provide necessary P.S. so that the piping is self standing and it imposes no strain on the pump casing.

- Ask the recommendations of pump manufacturer for the piping set -up.

P.S. How the inlet pipe is connected to reservoir ? İs the reservoir connection axial thrust resistant ? ( e.g. with puddle pipe and flange ?)..

Good Luck..

RE: Dismantling joint on pump suction

Bahman07

(Mechanical)

(OP)

27 Feb 21 13:55

Hi
I Can not provide isometric with support now. In suction run there are a butterfly valve, ecc reducer and expansion joint. On discharge check reducer and check and butterfly valve has been considered.
the inlet pipe connected to puddle pipe.
Thanks for your answers.

RE: Dismantling joint on pump suction

TugboatEng

(Marine/Ocean)

27 Feb 21 15:57

With that big U bend you eliminate the need for dismantling joints as the U can be easily removed to facilitate service of the pump provided your team doesn't mind doing a little bit of rigging as your pipe is quite heavy at that size.

RE: Dismantling joint on pump suction

Bahman07

(Mechanical)

(OP)

28 Feb 21 05:50

TugboatEng, in previous post, you suggested, using dismantling joint and removing expansion joint on suction, why this is better and not expansion without dismantle?
sorry I thought about it after my last post.

RE: Dismantling joint on pump suction

-44

(Petroleum)

28 Feb 21 06:33
Elimination of ANY expansion joint is well worth the effort.

You have not been paying attention.Elimination of ANY expansion joint is well worth the effort.

RE: Dismantling joint on pump suction

TugboatEng

(Marine/Ocean)

28 Feb 21 16:06

Honestly, I was a little confused. Dismantling joints don't exist in the marine industry. Properly installed, the expansion joint serves as the dismantling joint.

RE: Dismantling joint on pump suction

-44

(Petroleum)

28 Feb 21 21:04

Yeah. Even when you don't want it to.

RE: Dismantling joint on pump suction

Bahman07

(Mechanical)

(OP)

28 Feb 21 21:06

Sorry TugboatEng, I had to mentioned HTURKAK.

RE: Dismantling joint on pump suction

2

HTURKAK

(Structural)

1 Mar 21 05:56

Quote (Bahman07

Sorry TugboatEng, I had to mentioned HTURKAK.)

Quote (Bahman07
TugboatEng, in previous post, you suggested, using dismantling joint and removing expansion joint on suction, why this is better and not expansion without dismantle?
sorry I thought about it after my last post.)

Dear BAHMAN, regarding the above question , you want to ask the question to me but with mistake, you mentioned mr. TugboatEng. Is that correct?
If thaht is so,

I never proposed expansion joint and qualified that the use of expansion joint shall be approved , recommended by the pump manufacturer. In your case, The driver 355 kW , if expansion joint is used at pressure side, the thrust developing shall be resisted by pump body and foundation. Moreover, the pressure pipe will experience unbalanced high loads which may buckle if not properly supported.

With your proposed piping, i proposed fixable dismantling joint at inlet side but not expansion joint. and for pressure side, no dismantling joint, no EJ. since one can facilitate the repair just by loosening the dismantling joint at inlet side.

The horizontal bend 45 degr. complicating the force transfer. I am not sure how the developing thrust is transferred to the PS.'s.

Good Luck..

Dear BAHMAN, regarding the above question , you want to ask the question to me but with mistake, you mentioned mr. TugboatEng. Is that correct?If thaht is so,I never proposed expansion joint and qualified that the use of expansion joint shall be approved , recommended by the pump manufacturer. In your case, The driver 355 kW , if expansion joint is used at pressure side, the thrust developing shall be resisted by pump body and foundation. Moreover, the pressure pipe will experience unbalanced high loads which may buckle if not properly supported.With your proposed piping, i proposed fixable dismantling joint at inlet side but not expansion joint. and for pressure side, no dismantling joint, no EJ. since one can facilitate the repair just by loosening the dismantling joint at inlet side.The horizontal bend 45 degr. complicating the force transfer. I am not sure how the developing thrust is transferred to the PS.'s.Good Luck..

RE: Dismantling joint on pump suction

Bahman07

(Mechanical)

(OP)

3 Mar 21 06:46

Quote (HTURKAK)

Dear BAHMAN, regarding the above question , you want to ask the question to me but with mistake, you mentioned mr. TugboatEng. Is that correct?
If thaht is so,

I never proposed expansion joint and qualified that the use of expansion joint shall be approved , recommended by the pump manufacturer. In your case, The driver 355 kW , if expansion joint is used at pressure side, the thrust developing shall be resisted by pump body and foundation. Moreover, the pressure pipe will experience unbalanced high loads which may buckle if not properly supported.

With your proposed piping, i proposed fixable dismantling joint at inlet side but not expansion joint. and for pressure side, no dismantling joint, no EJ. since one can facilitate the repair just by loosening the dismantling joint at inlet side.

The horizontal bend 45 degr. complicating the force transfer. I am not sure how the developing thrust is transferred to the PS.'s.

Good Luck..

YOU ARE RIGHT
THANKS FOR YOUR REPLY.

YOU ARE RIGHTTHANKS FOR YOUR REPLY.

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