Hello! I’m Doug Riseden, technical support manager for Hymax USA. Here’s a tip on measuring ODs and an answer to the question about the center bolt on large HYMAXs.

HYMAX ODs and Gaskets – Measure twice and remove once!

Measuring the pipe OD is critical to knowing if a HYMAX gasket should be removed during installation since once it’s taken out, it can’t be put back in. The adage “measure twice, cut once” can be adapted to “measure twice, remove once” when it comes to ODs and gaskets.

Here are some tips on knowing when to remove a HYMAX gasket.

• Read the directions right on the HYMAX about when to remove the inner gasket and when not.
• Make sure that you clean the pipe before measuring the pipe’s OD. Use a pipe descaler and wipe the pipe down to remove anything to prevent an inaccurate measurement.
• Measure the pipe OD once…and measure it again. The HYMAX is a full transition coupling so make sure you have the ODs for both pipes entering the coupling.

Do I need the center bolt on the Large HYMAX and large HYMAX Reducers?

I’m frequently asked why there is a center bolt on the large HYMAX and large HYMAX reducers.

This bolt is there to prevent the clamp from slowly moving or “creeping” down the pipe as the clamp is tightened, and maintains the clamp in the intended position. Without the bolt, it’s difficult to know if the pipes are centered evenly.

For the large HYMAX, simply cut the new section of the pipe two inches shorter than the pipe that is being removed. The one inch center bolt will fit in the area between the new and old pipes. There are two sets of these centering bolts on the large HYMAX reducers since the pipes on either side of the clamp are different sizes.

I’ve also been asked by those using the HYMAX in waste water applications if the bolt can be cut given their concern of waste water solids catching on the center bolts. It’s fine to do this but keep in mind that you will lose the bolt’s anti-creep capabilities in the process.