Expansion joint life issues

This depends on the quality of the manufacturer's product. If the quality is better, the service life should be longer. If the quality is poor, it may need to be replaced after less than a year. However, our factory has used imported ones and I heard that they can be used for at least ten years. They were installed in 2003 and have not been replaced yet, and everything is in normal use. You can make a decision based on the actual situation. If it is indeed good, there is no need to spend the extra cost. You can wait until you pay for it for a period of time before you decide. It is not too late to change it when it is absolutely necessary.

PC series expansion joint types for petrochemical industry: Single axial type, compound free type, single hinge type, single universal hinge type, compound hinge type, compound tie rod type, elbow pressure balanced type. Expansion joint nominal diameter: 500-4800mm expansion joint design pressure: 0.35MPa maximum design temperature of bellows: 350℃, 750℃ bellows design fatigue life (weeks): 3000 Main uses: The process pipeline of catalytic cracking refining unit with medium temperature below 1300℃. CSRW series expansion joint types for heating network engineering series: Single axial type, external pressure single axial type, single hinge type, compound tie rod type. Expansion joint nominal diameter: 50-1600mm expansion joint design pressure: 0.25-4.0Mpa maximum design temperature of bellows: Design fatigue life of bellows at 350℃ (weeks): 1000, 500, 200 Main purpose: The centralized heating pipe network is laid overhead in trenches with steam and hot water media below 450℃. Metal bellows expansion joint components ZM series expansion joint types: Single axial type, external pressure single axial type. Expansion joint nominal diameter: 50-1200mm expansion joint design pressure: 0.25-1.6MPa maximum design temperature of bellows: Design fatigue life of bellows at 350℃ (weeks): 1000, 200 Main purpose: The steam and hot water medium below 450℃ shall be compensated and directly buried to lay a centralized heating pipe network. YZM series expansion joint type: External pressure compound axial type. Expansion joint nominal diameter: 50-1400mm expansion joint design pressure: 1.6MPa maximum design temperature of bellows: 150℃ bellows design fatigue life (weeks): 200, 1000 Main purpose: The hot water medium below 150℃ shall be compensated and directly buried to lay a centralized heating pipe network. MZ series expansion joint type: Single axial type. Expansion joint nominal diameter: 50-1200mm expansion joint design pressure: 1.6MPa maximum design temperature of bellows: 150℃ bellows design fatigue life (weeks): One-time direct burial. Main purpose: The hot water medium below 120℃ shall be directly buried and laid in one-time compensation for central heating pipe network. CQ, CY series CQ series expansion joint types for ships: Single axial type. Expansion joint nominal diameter: Round type 65-800mm. Expansion joint design pressure: 0.1MPa maximum design temperature of bellows: 550℃ bellows design fatigue life (weeks): 5000. Main purpose: Exhaust piping system for ship engines below 550℃. CY series expansion joint type: Round axial type. Expansion joint nominal diameter: 50-500mm. Expansion joint design pressure: 0.6-1.6MPa maximum design temperature of bellows: Design fatigue life of bellows at 200℃ (weeks): 3000. Main purpose: Ship seawater, fresh water, oil or steam pipeline systems with temperatures below 200°C. HR series expansion joint types for heat exchangers: Single axial type. Expansion joint nominal diameter: 150-4200mm. Expansion joint design pressure: -0.1-10.0MPa bellows design temperature: Design fatigue life of bellows at 350℃ (weeks): 3000 Main uses: Pressure vessels such as heat exchangers with medium temperatures below 350°C. Customized according to user requirements. SN series expansion joint types for cement industry: Round single type axial type, rectangular single type axial type. Expansion joint nominal diameter: Circular 200-3200mm, rectangular pipe cross-sectional area ≤ 9M2 expansion joint design pressure: 0.05MPa maximum design temperature of bellows: 400℃ bellows design fatigue life (weeks): 1000, 3000. Main purpose: Micro-pressure dust gas, liquid medium cement plant process pipeline with medium temperature below 1000℃. YD series expansion joint types for metallurgical power engineering: Single axial type, single hinge type, straight pipe pressure balanced type, compound tie rod type, elbow pressure balanced type. Expansion joint nominal diameter: 200-3000mm expansion joint design pressure: 0.1-2.5MPa maximum design temperature of bellows: Design fatigue life of bellows at 350℃ (weeks): 1000 Main uses: The medium temperature is below 350℃ and below 1300℃ for gas and liquid medium metallurgical plants and power plant process pipelines.

The pipeline has been in operation for 13 years and uses external pressure bellows expansion joints. The material is 1Crl8Ni9Ti and the treatment method is solid solution treatment.

Thank you everyone for participating in the reply. I have a question. Please explain it.: What is the concept of fatigue life (weeks)? What is the number of tests? And how to determine reality?

If the part is not important, it can be used. If it is a very important part, it should be replaced, safety first. Also, will its failure have any impact on the long-term operation of the device? Is maintenance convenient?

Fatigue life refers to the number of reciprocating movements that can be completed under certain conditions such as pressure, temperature, corrosion, etc. The displacement of the reciprocating motion is the thermal expansion and contraction of the pipe due to temperature changes. You can calculate this amount based on specific working conditions.

We haven't had it replaced in 10 years.

The main thing is to look at the corrosion degree of the expansion joint itself. The main thing is to look at the welding seam of the bellows itself and the welding seam between the bellows and the pipe. The bellows of the expansion joint at the outlet of the hood is mainly produced from 800 series and 625 series alloys. It has strong corrosion resistance. If the manufacturer has excellent production quality, there is generally no problem.

In the standard GB 16 7 4 9-1 9 9 7 pressure vessel corrugated expansion joints, the calculation formula and chart information for the number of fatigue cycles can be found, and the calculations can be compared with the actual quantities.