Sorry Maine...I gotta disagree.
I don't think any pipe dope/sealant is appropriate for use in any plumbing system or especially in any sanitation system plumbing because it creates the illusion that it's a permanent fix...and NOTHING on a boat is a permanent fix!
The ONLY thing that ever be used in sanitation plumbing is Teflon tape or paste.
Peggy,
The ONLY thing permanent about Real-Tuff or Megaloc is the permanence of leak free fittings!
Try telling that to the millions and millions of owners of plumbing, sanitation and heating systems throughout the world whose threads are sealed with pipe dope/tape, pipe dope alone (the most common practice) or tape. Plumbers, heating specialist and pipe fitters live and die by pipe dopes for mating NPT-NPT fittings every day. One call back due to a leaking fitting can cost you half a days work. Iorked in that industry as a manufacturers rep for many years and sold pipe dopes and teflon tapes for one of the biggest manufacturers in that market so I do understand how these things work or don't. There are some pipe dopes not worth the cans they ship in but you'd not hear me recommending them here.
The OP was asking about seacocks. Seacocks are usually bronze or Marelon and use sealing threads. Pipe dope, no matter who makes it, is the world standard for sealing threads.
Sadly you are clearly confusing a PLUMBING pipe dope like Real-Tuff with 5200 or something else.
Real-Tuff is a THREAD SEALING dope that does not harden or fully cure. It is meant to both seal, by filling in any thread imperfections, and lubricate the threads so the NPT to NPT can thread together without galling or prematurely binding, and create a liquid and gas tight seal. The product I recommended, Real-Tuff is a PTFE based dope made of the SAME stuff as teflon tape, PTFE. Adding this dope to tape takes the level of sealing to nearly 100%, 100% of the time repeatably even in significantly higher working pressures than we have to deal with on boats. This product, unlike some dopes, is 100% safe for plastic pipe fittings too as it contain no harsh solvents.
I would NEVER recommend a product like a marine "sealant" such as 4200 or 5200 for thread sealing. Real-Tuff is NOT permanent at all. It in fact actually ALLOWS the products to come apart much easier in the future.
If you don't understand or know of the product you might look into it first before getting on me about being wrong..
Personally I would never trust just tape or just dope. I have seen far to many examples of plumbers & pipe fitters & boat yards and DIY's who only used one or the other, and also the results of the guys who took the time to use both.
The ONLY thing that ever be used in sanitation plumbing is Teflon tape or paste.
Real-Tuff COMPLIMENTS teflon tape and IS teflon paste!!!!
You might buy a can of Real-Tuff and I'll bet you'll be on here recommending it by next week..
Real-Tuff Data Sheet:
Multi-purpose heavy duty, white, PTFE paste thread sealant for use on Aluminum, Black Iron, Brass, Copper, Glass, Monel, Natural Rubber, Plastic (P.E.,Reinforced), PVC, ABS, CPVC, Stainless Steel, Synthetic Rubber (Butyl, Neoprene). Contains a unique system of fine grain PTFE particles specifically designed to fill cracks and tiny thread imperfections. Leak free joints can be tested and put into service at once. Real-Tuff holds tight against expansion, contraction and vibration, is non-separating, will not run or drip from joints, contains no lead. Non-hardening lubricating formula permits low torque make-up and easy disassembly without galling or stripping threads. Real-Tuff withstands temperatures from -200°F to +550°F, and provides leak-proof hydraulic resistance to 12,000 psi. Withstands gas pressure up to 2,600 psi. Real-Tuff is non-flammable and contains no heavy metals or volatile solvents and is applied easily with a natural bristle brush, even at temperatures as low as -25°F.
