It cannot be stressed too highly that Y-strainers must be designed with adequate safety margins. This means sufficiently heavy wall thickness and blow off connections. As an example, in improperly trapped steam lines, condensate can collect in low points and become a slug of water traveling at very high velocity down the line. Even the slight change in direction caused by a Y-strainer can produce a tremendous shock which can break the strainer wall. Manufactures who thin down walls to save weight and cost are asking for trouble in these cases.
A Y-strainer is, in a sense, a self-cleaning strainer. Many are fitted with a blow off connection to which a valve can be attached. The screen can thus be cleaned by simply opening and then closing the valve without shutting off the flow or disassembling the strainer. The old saying “a chain is no stronger than its weakest link” applies here, a Y-strainer is no stronger than its clean-out connection. These features should always be checked. In large sizes where the clean-out connection is flanged, the flange must not be skimpy. It should also be properly gasketed. Fro high temperatures or pressures, metallic reinforced gaskets should be used.
Another important design feature to check for in Y-strainers is the point where the screen or straining element seals to the body. This seat should be carefully machined so no particle can bypass it. The same thing applies to the clean-out end. The screen should fit tightly. Beware of strainers with un-machined seats.