Metal Expansion Joints and Metallic Compensators
Design of Metal Expansion Joints
The design of a metal expansion joint and metallic compensator stage begins in the Technical Department, composed by a technical staff & engineers specialized in the calculation and design of expansion joints.
Our metal expansion joints are designed according to different international codes, as EJMA (Expansion Joint Manufacturers Association), ASME Section VIII Div.1, AD-MERKBLÄTT B-13, CODAP or British Standard.
We count on the lastest information technology tools for the calculation, Finite Elements Method (FEM), simulation (3D) of the components of the metal expansion joint.
Manufacturing of Metal Expansion Joints
Depending on the diameter and on the application, the bellows can be manufactured by hydraulic or mechanical forming:
- The hydraulic forming ensures a perfect distribution of the stresses caused by the deformation and of the thickness along the wave. In this way, these bellows can be used for the most stringent conditions, as in nuclear applications.
- The mechanical forming enlarges the manufacturing range (different diameters, number of waves, wave height, number of passes, etc.), what allows to optimize to the utmost the design of the compensator.
Welding of Metal Expansion Joints
The welding is the key factor in the manufacturing of metal expansion joints. The welding is an indispensable feature in our equipment, and this task is done with the highest quality standards.
The welding of the bellows is done in an automatic process, by means of state-of-the-art machinery for a minimum thickness of 0.2 mm and with different welding procedures as GTAW (TIG) or MICRO PLASMA (PAW).
For the rest of the welding we have at our disposal welding machinery for different processes as GTAW [TIG], ORBITAL GTAW, GMAW [MIG-MAG] and SMAW, as well as we can do many of them in an automated way.
Materials for Metal Expansion Joints Manufacturing
The most usual materials used in the manufacturing of our metal expansion joints are austenitic stainless steels, as SS304 (1.4301), SS 304L (1.4306), SS 316 (1.4401), SS316L (1.4404), SS 316Ti (1.4571), SS 321 (1.4541), up to temperatures of 600°C, or the 1.4828 [SS309S] up to temperatures of 1000°C.
In our scope of supply, we can also use Nickel based alloys as INCONEL 600, INCONEL 625LCF or INCOLOY 825.
For the rest of the components of the metal expansion joint, different materials can be used, as all kind of carbon steels, alloyed steels or duplex stainless steels.
Inspections and test in Metal Expansion Joints
These inspections are carried out according the procedures and guidelines approved by our Quality Department, which certifies those tests, or by external recognized agencies, always done by qualified workers.
We guarantee the manufacturing of our equipment by means of different quality controls. We are listing some of them as follows:
- Inspections of raw materials reception
- Visual inspection and dimensional control at all stages of manufacturing
- X-Ray tests of welding
- Die penetrants / magnetic particles
- Ultrasounds
- Pressure tests (hydraulic)
- Leak testing (air, helium)
- Materials identification (PMI)
- Others
Authorised Independent Bodies and Approved Entities
The manufacturing and inspections can be supervised and certified by an authorised independent body and approved entities:
- SGS
- APPLUS
- EUROCONTROL
- Lloyd´s Register of Shipping (LR)
- Det Norske Veritas (DNV)
- Bureau Veritas
- Germanischer Lloyds(GL)
Corrosion issues in metal expansion joints
The service life of a metal expansion joint or metallic compensator can be drastically reduced due to corrosion issues. The design and operation conditions can influence meaningfully, in such a way that the bellows may be affected by corrosion issues whilst the surrounding pipes and supports may not, even though they are made of similar materials.
Metal Expansion Joints Main Elements
There are many design alternatives, depending on the elements that make up the metal expansion joint or compensator.
Typical Causes of Metal Expansion Joints Failure
Our know-how designing and manufacturing metal expansion joints and metallic compensators since 1978, has shown us that certain breakdowns rest most of the time with the same mistakes or incidences, such as those set out in the following sections.