TECHNICAL ARTICLE case
EXPANSION JOINT INSTALLATION AND MAINTENANCE
Let’s talk about Expansion Joint installation and maintenance guidelines. The calculated service life of a Expansion Joint is based on the precondition that the Expansion Joint will never be subjected to mechanical or thermal load exceeding the stated design data. In order to achieve the maximum service life, pressure resistance and reliability, caution should be taken during Expansion Joint handling, Expansion Joint storage and Expansion Joint installation. The necessary care should include taking the following advice. Failure in the Expansion Joint installation to comply with the installation instructions could reduce the service life and pressure capacity of the Expansion Joint, which could lead to damage or at worst breakdown of the Expansion Joint or the pipe system. Here Expansion Joint installation and maintenance guidelines is described more in details:
EXPANSION JOINT STORAGE AND TRANSPORT
We recommend that a visual inspection is carried out immediately on receipt of delivery of the Expansion Joint to ensure that it has not been damaged during shipment.
- Transport fittings, tie rods, hinges or gimbals should not be used to sling and lift the Expansion Joint. The Expansion Joint should not be lifted by slings or chains around the Bellows and must not be lifted in a manner, which causes the Bellows to be subjected to mechanical loads.
- The Expansion Joint must not be subjected to torsion during handling and installation.
- The Expansion Joint should be stored on an even, solid surface in a clean and dry environment under a roof or other rainproof cover.
- Expansion Joints should not be stacked on top of each other or knocked against each other.
- If the weight of the end fittings tends to cause the Bellows to bend the ends should be braced using wooden supports.
- Care should be taken to avoid mechanical damage as well as damage by water, moisture, sand, soil, building materials and chemicals.
Transport fittings/pretensioning fittings on the Expansion Joint
Transport and pre-tensioning bars will be identified by yellow and black striped tape. These fittings must NOT be removed until the Expansion Joint installation. If these devices are removed prematurely, the Expansion Joint may move to an incorrect condition and could possibly endanger people working in the vicinity. Furthermore, premature removal could cause the Expansion Joint not to function as intended, which could result in reduced service life or at worst breakdown of the Expansion Joint.
EXPANSION JOINT INSTALLATION
Installation should be carried out by suitably trained and competent staff working in compliance with relevant legislation and regulations for occupational safety.
Prior to Expansion Joint installation
Unless clearly stated in the design data of the Expansion Joint, the Expansion Joint is not designed to compensate for installation inaccuracies in the piping and must not be used to connect them. Prior to Expansion Joint installation, the Expansion Joint should also be checked that it is undamaged and has no dents, damaged fittings and water marks on the steel (incipient rust) etc. It should also be checked that:
- The Expansion Joint is free from foreign objects such as insulation materials, dirt or debris.
- Sealing surfaces on flanges are even and clean.
- The gap in the pipeline where the Expansion Joint is to be installed matches the specified installation length of the Expansion Joint with design tolerances taken into account. The Expansion Joint must be fitted at the length stated in the specifications.
- The connecting ends of the pipeline are clean and correctly prepared for welding.
- The installation location of the Expansion Joint in the pipeline complies with that determined by the system designer.
- The expansion of the pipeline is in accordance with the design data of the expansion joint.
- The adjacent pipework is correctly installed with anchors, guides and supports in place.
- Anchors must be adequate to accept reaction forces from the Expansion Joint and all other pipework loads.
- Only one Expansion Joint is fitted between two anchors.
- Tie rods on Lateral Expansion Joints are correctly fitted and are secure.
Anchors and guides on the pipeline must be placed as per the guidelines in EJMA so that:
- The Expansion Joint is not subjected to dead-weight loads from the pipeline.
- The pipeline does not sag, “hog” or “snake” between anchors or guides.
- Drop rods or hanger rods should be avoided, guides should be slide or roller type.
- When using Expansion Joints the distance must not exceed 4 x the nominal diameter of the pipeline.
- The distance between the first and the second guide must not exceed 14 x the nominal diameter of the pipeline.
- The distance between the remaining guides must not exceed 21 x the nominal diameter of the pipeline. This distance must be reduced if this is necessary in order to stabilize the pipeline.
During Expansion Joint installation
- When welding or grinding near the Expansion Joint it should be protected against weld spatter and debris, we recommend use of a chloride free welding blanket.
- Care must be taken to avoid accidental arcing on the thin-walled bellows in the Expansion Joint.
- The Expansion Joint should be protected from damage caused by adjacent construction work, splashes from mortar or plaster can damage the Expansion Joint and must be avoided.
- If the Expansion Joint is equipped with an inner sleeve, make sure the flow arrow on the Expansion Joint points in the direction of the system flow.
- When fitting Angular Expansion Joints it is important that the hinge pins are in the correct orientation.
- Do not apply torsion to the Expansion Joint to align the bolts on flanged units.
- Components such as tie rods, hinge links and gimbals must not be removed. They form part of the integrity and functionality of the Expansion Joint.
- Care should be taken with fitting tools, to not damage the Bellows with spanners or wrenches when tightening bolts.
- On flanged units ensure that over-long studs or bolts do not contact and damage the Bellows.
- When Expansion Joints are supplied without external covers and insulation is to be added, a lagging cover should be fitted to prevent insulation material becoming trapped between the bellows convolutions where it can prevent the Bellows from functioning correctly.
On completion of Expansion Joint installation
Before the completed system is tested and commissioned, it should be subjected to a visual inspection. Many years experience have shown that careful checking of the installation before pressure testing and final commissioning will help to ensure successful Expansion Joint installation and performance. Before pressure testing and as part of the inspection regime ensure that all temporary shipping and pretensioning devices (marked by yellow and black striped tape) are removed from the Expansion Joint.
Pressure test must be carried out according to the stated test specifications on the drawing and/or the tag plates on the Expansion Joint.
Prior to pressure testing
CHECK THE FOLLOWING
- Has the Expansion Joint been damaged during the expansion joint installation?
- Is the entire pipe system, especially anchors, guides and expansion joints, installed as shown in the drawings in the installation instructions?
- Is the Expansion Joint correctly fitted into the system and not used to correct fabrication inaccuracies?
- Is the flow direction of the Expansion Joint correct?
- Are the bellows and other moving parts on the Expansion Joint free from foreign objects such as insulating material?
- Have all shipping bars, pre-tensioning devices, protective parts and packaging materials been removed?
- Have all guides, supports and Expansion Joints been released to allow the expected movements in the pipe system?
- If the system is designed for a light flow medium such as air or gas and is to be tested with a heavier medium such as water have the necessary steps been taken to ensure that the extra dead-weight loads to the Expansion Joint and pipe system can be safely accommodated?
During pressure testing
CHECK THE FOLLOWING
- The pressure should be increased gradually until the specified test pressure is reached.
- Check the Expansion Joint for any sign of leakage at the connections and check the gauges for pressure drops.
- Examine the Expansion Joint for any signs of twisting, instability, squirming at the bellows or unexpected movement of any of its components.
- Any unexpected movement of the pipe system which could be pressure-related should be investigated and addressed.
After pressure testing
CHECK THE FOLLOWING
The Expansion Joint and pipe system should remain as designed, in particular check that the anchors and their attachments to civil works or structure do not display any signs of distress. It should be noted that after testing some residual testing fluid may remain in the bellows, if this is likely to affect the functioning of the system arrangements to remove the fluid may be necessary.
- Dropping or knocking the bellows.
- Using cleaning agents containing chlorides.
- Using steel wool or steel brushes on the bellows.
- In case of any doubt the pressure test should not exceed more than 1½ x the design pressure without previous written confirmation from us.
EXPANSION JOINT MAINTENANCE
A correctly dimensioned and correctly installed Expansion Joint does not require any special maintenance other than the inspection that is carried out for the other parts of the pipe system in which the Expansion Joint is installed. We recommend that you carry out ongoing inspection of the pipe system throughout its service life. The aim of these inspections is to check for the presence of rust, whether parts have come loose, etc. The frequency of these inspections is determined on an individual basis based on the function of the system, occurring loads and so on. The above does not guarantee that damage will not occur, but it does significantly reduce the risk. It may be useful to know the common causes for faults in Expansion Joints. However, it is difficult to list all general maintenance directions as Expansion Joints have a wide field of application and many Expansion Joints are constructed for a specific application. We would like to draw your attention to the most common causes for failures below:
Shipping and handling damage
- Knock-damage, dents, scuffs and scratching of the bellows caused by incorrect handling or inflicted after Expansion Joint installation.
- Unanticipated detrimental influences from the environment such as corrosion caused by salt, chemicals or the like in the atmosphere.
Expansion joint installation damage and installation errors
- Incorrect location – Expansion Joint installation at a position in the pipework not intended by the system designer.
- Using the Expansion Joint to correct fabrication errors without first confirming this is acceptable with the designer.
- Fatigue failure caused by movements for which the Expansion Joint was not designed, especially lateral movements.
- Damage caused by accumulation and packing of foreign material between the bellows convolutions, that can affect the bellows internally or externally.
- Overpressure in the pipe system.
- Premature removal of shipping or pretensioning devices or failure to remove them after installation.
- Damage from weld spatter due to lack of protection during Expansion Joint installation.
- Installation of units fitted with flow liners with the liner against the flow direction.
- Corrosion damage caused by the flow medium, in particular chloride presence.
- Fatigue failure owing to unforeseen vibration in the system.
More detailed information on Expansion Joint installation and maintenance guidelines & explanatory illustrations
Having gone through Expansion Joint installation and maintenance guidelines, please note that in the Belman installation instruction you can find more information and explanatory illustrations etc. about optimum Expansion Joint installation.
This installation instruction is always send with Belman’s Expansion Joints. To further help the client the Expansion Joint installation instruction is multilingual, and therefore contains the instructions in among others; English, German, French, Spanish, Polish, Russian and more.
If you have any questions or any doubt about the Expansion Joint installation procedure, please do not hesitate to contact us