Stepped Vs Flexible Coupling - Pipe Fitting

Of course it can be done. If it couldn't be done then a flexible coupling would not exist.

Is it safe for you to use in your application a flexible coupling instead of stepped coupling called for by somebody else? Well this requires more information than you've given us to answer properly. My first thought would be to consult with whomever told you to use a stepped coupling. Bring them the data sheet about the flexed coupling. This may be able to tell them if the coupling will handle the pressure, corrosives, bacteria, purity or other concerns for the media inside the pipe. This will also show them that you can think well enough that an explanation why this can or cannot be used will not fall on deaf ears.

If you tell them nothing when you ask for guidance then you just look like a fool that barely has enough intelligence to turn a wrench the correct direction half of the time.

Of course it can.

Plastic can be substituted for metal.

Bubble gum can be substituted for pipe sealant.

Spaghetti can be substituted for tubing.

The possibilities are almost limitless, if there are no rules to follow.

The term "stepped coupling" is unusual. Do you mean a reducer, which could be either concentric or eccentric? Most if not all flexible couplings are one size only, so if the pipe size changes, they wouldn't work.

If by a "stepped coupling" you mean a reducing coupling (such a 2" x 1-1/2 reducing coupling) it can be done if a few parameters are followed.

If flowing hot water or steam through the pipe make sure the temperature rating of flexible coupling is rated for the temperature.

The flexible coupling is rated with a safety factor for the pressure of the system.

Both pipes must be very secure and rigidly held in place (hangers, straps, etc)

The flexible coupling is intended for coupling misaligned pipes end to end. Make sure there is sufficient length to the flexible coupling to not strain it.

The materials of the flexible coupling are compatible with the material in the pipe.

If these can not be met try a flexible pipe. They usually have a flexible inner lining supported by an exterior woven stainless steel braided mesh. This with a couple of other pipe fittings would do the job, possibly better.

Good Luck, Old Salt

By a step coupling I can only assuming you mean a reducing coupling or a swage reducer or some other type of reducing fitting?

1st It will depend on your product, temperature and pressure in the line.

2nd it will depend on the material you are using in the flex fitting. Is it Rubber, plastic, Stainless Steel or what?

3rd and finally it will depend on where you use it. Pump Suction require an Eccentric Reducer to remove any air bubbles that may cause problems at the impeller of the pump. So that would be a NO! You can install a flex fitting downstream of the eccentric reducer but this may also cause turbulence on the pump suction so up-steam would be better.

4th Is the equipment you are hooking up to have a vibration?

So I suggest you resubmit your question with more information so we may provide you with the correct answer!