You want to work with an expansion joint manufacturer you can trust and that will be in your best interests. An experienced expansion joint designer will take the guesswork out. It can be difficult to choose the right expansion joint configuration or bellows material.
My goal as a designer engineer is to offer my customers the most cost-effective, long-lasting expansion joint products. However, I must get all the information from my customers in order to achieve this goal. It can be frustrating for people to not take the time necessary to learn all the details. Expanding joints are not a standard size for all products.
It is cheaper to design for each application than to make them all the same. Sometimes, customers don’t do enough research and the expansion joints or metal bellows end-up costing more than they should.
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DO NOT GUESS! Find out the temperature and pressure if you don’t know! Someone has this important information. You shouldn’t assume that the expansion joint you are replacing has 150# flanges. Instead, you should look for an expansion joint that is rated at 150 psig. This assumption could get you into trouble and cost you more than you need to purchase a product that won’t last as long.
A 150# forged steel class 150 flange can actually be rated for 285 psig @100of. Your expansion joint manufacturer may only design the bellows for 150psig. If you make a mistake, a failure could occur at higher pressures. Oops! OOPS! It is a good rule of thumb that the heavier the bellows material, the higher the pressure. The material and labor costs will be higher if the bellows material is thicker. The theoretical life expectancy of a material with a thicker thickness is lower.
Your metal expansion joint supplier should know that you require multi-ply bellows construction. Metal bellows with multiple layers of material will last longer than single-ply bellows made from thicker sheet metal. Multi-ply bellows are cheaper than single ply bellows. The bellows element in the piping system is the weakest link, so why not make sure it performs at its best with multi-ply designs?
Ask your bellows supplier for a design data sheet. This will give you peace of mind. Your expansion joint’s metal bellows should be manufactured and designed in accordance to the Expansion Joint Makers Association.
Some of the information in the printout might not be relevant to you, but there are still things to consider. Check that the bellows are designed to maintain the right pressure and temperature.
Verify that both the lateral and axial movements are correct. It is important to know how long your expansion joints can last theoretically. For example, the data sheet for a single plly bellows is calculated to last 300 cycles.
Your expansion joint would stop working if it cycled only once per day. If you are unhappy with the cycle life and spring rates offered by your supplier of expansion joints, let them know. While some expansion joint companies will try to sell you new expansion joints every year, you as a consumer can make better choices. My best advice is to trust a metal bellows manufacturer of expansion joints.