While CSST tubing meets all US plumbing
codes, I have some concerns of its suitability on boats. The tubing is very thinwall tubing with a maximum working pressure of only 5 psig. The fittings are brass.
The issues with it are several.
First you have cheap
brass fittings with a high zinc content in contact with the stainless steel tubing. There are galvanic issues between the tubing, fittings and sealing ring in a salt
. The manufacture recommends sealing the ends with silicone tape if exposed to weather
. Myself I don't think that would be adequate in a salt
Second the pressure rating is only 5 psig and the material is designed to be installed in buildings that generally do not heel over much. I am concerned that with the boat working in a seaway that over time, the thin tubing may wear as it passes through bulkheads, etc.
That, and with a really low working pressure, to me makes it less then desirable to use on boats. Most hose for propane or CNG will have a 200 to 325 psig working pressure. Mainly as propane pressures can exceed 150 psig in a hot tank.
CNG is stored at 3000-3600 psig. If the gas pressure regulator
failed open (which can happen though rare) the hose needs to be able to contain the pressure of the propane or the CNG second stage regulator
. CSST tubing will not do that.
For those reasons, I don't think CSST tubing would be safe on a boat. But that's just me. The hose in my link on the other hand was tested to 750 psig without bursting.