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Analysis of Metal Bellows Expansion Joint Failure

2017/2/17 14:38:24      Click£º

Metal bellows expansion joints of our company have been properly designed and produced to apply in various piping systems. However, failures of metal bellows expansion joint have occurred, users and metal bellows expansion joint manufactures both are possible causers. Although metal bellows expansion joint failures can occur for many reasons, Lanphan¡¯s rich experiences has concluded several certain typical causes of failure as below.

1. Incorrect installation method and insufficient protection measure for the metal bellows expansion joint.

2. Something you do during and after installation. For instance:

Joints with internal liners installed in the reverse direction with respect to flow;

Installing a metal pipe expansion joint in a location other than as prescribed by the installation drawings;

Premature removal of shipping devices;

Springing of metal bellows expansion joint to make up for piping misalignment;

Insufficient protection from mechanical damage due to work in the surrounding area; Insufficient protection of bellows during nearby welding operations and failure to remove shipping devices before placing system in operation.

3. Exceed pressure of the system (in-service or hydro test) and bellows vibration (mechanical or flow induced resulting in high cycle fatigue)

4. Metal bellows expansion joints erosion and torsion.

5. Packing of particulate matter in the bellows convolutions which inhibits proper movement of the bellows.

6. Shipping and handling damage. For instance:

Denting or gouging of bellows from being struck by hard objects (tools, chain falls, forklifts, adjacent structures, etc.);

Improper stacking for shipping or storage;

Insufficient protection from weather or other adverse environmental conditions.

7. Improper anchoring, guiding and supporting of the system.

8. Internal and external metal bellows expansion joints corrosion.

9. Excessive bellows deflection, that is axial, lateral, angular deflections greater than design values.

10. Also anchor failure in service.