Are BOSHART BPF and SSPF Push-Fit fittings approved for underground use?

Yes. Both the BOSHART BPF brass and SSPF 304SS push-fit fittings are approved by IAPMO for underground applications. Both Brass and 304SS can corrode to some degree when exposed to severe ground conditions.

To use BOSHART BPF and SSPF Push-Fit fittings underground they must be wrapped to ensure that no foreign debris / aggressive soil is allowed to enter the fitting body which could result in crevice corrosion and / or interference with the internal SS gripper ring, release collet and O-ring components. Self-fusing silicone tape protects both brass and stainless-steel fittings from corrosive soil conditions and / or contaminants that can be found in the soil. Brass Push-fit fittings like any other fittings made of brass, are susceptible to both corrosion and dezincification.

While 304SS push-fit fittings provide superior corrosion resistance and are not affected by dezincification like brass fittings are. Dezincification is a process which selectively removes zinc from a brass alloy, leaving behind a porous, copper-rich structure that has little mechanical strength. Stainless steel can perform remarkably well buried underground for long periods. However, when in contact with moisture and aggressive chemicals such as chloride ions, sulphates, and stray currents, it can cause localized corrosion This is why buried stainless steel fittings or piping require more consideration than above-ground stainless steel applications. Buried stainless steel can experience soil corrosion when it meets one or more of the following conditions: High moisture content, Presence of chlorides, sulphides and bacteria, Presence of stray currents, A pH value less than 4.5, A resistivity less than 2000 Ω · cm.

Failure to wrap the fitting(s) in any underground application will void the 25-year warranty.

How to Wrap Fittings for Underground Installation:

IMPORTANT: Always make sure to follow the guidelines for minimum bury depth in your area. Make sure to adhere to all applicable plumbing codes for direct burial applications.

The installation instructions below are to be used as a guide, always make sure to follow the manufacturer's instructions for applying the silicone pipe wrap to the fitting.

STEP 1 - After the connection is completed, determine how much self-bonding silicone pipe wrap is required. To do so lay the pipe in the trench and unroll the silicone wrap leaving the protective seal intact. Ensure the tape extends a minimum of 1-1/2 inches past the end of the fitting onto the pipe at both ends.

STEP 2 - Unwrap the protective seal from the cut piece of silicone tape, then apply the silicone wrap to the fitting. Using the same process as above cut additional pieces and work around the fitting overlapping the tape 1/2 the width of the tape, peeling away the protective seal enabling the tape to bond to itself. Continue wrapping until the entire fitting is covered. The silicone wrap will bond to itself within minutes and will cement in an hour or two. Bonding time may vary from one brand of tape to the next. 

STEP 3 - Cover the piping in a layer of sand and then backfill, making sure to remove all rocks and debris from the dirt to prevent damage to the piping due to impact or abrasion by foreign debris. Continue backfilling until the pipe is completely buried.