Caps + Plugs
In this category you will find over 220 stainless steel threaded caps and plugs. They are used to seal pipe ends and threaded connections in sanitary and irrigation systems.
Buying Caps + Plugs — Guide& Tips
Whether you want to permanently seal a pipe end or seal a threaded connection: caps and plugs made of stainless steel 316 (V4A) are the reliable solution for sanitary, irrigation and industrial applications. The 224 articles in this category cover a wide range of sizes – from small inch dimensions to dimensions for main lines. Three factors are crucial for the right choice: the material, the thread type and the place of use.
Stainless steel 316 (also V4A, AISI 316) is characterized by high corrosion resistance – even with permanent contact with chloride-containing water or aggressive media. The fittings are designed for pressures up to 10 bar and are suitable for both cold and hot water. When buying, pay attention to the exact thread designation: caps have an internal thread (IG) and are screwed onto a pipe; plugs have an external thread (AG) and close sockets or other fittings.
Always check the compatibility with your existing piping system before ordering. Measure the diameter and the pitch of the thread – if in doubt, a caliper helps. For drinking water installations, fittings with appropriate approval are recommended; for garden irrigation systems, standard versions sealed with Teflon tape are sufficient. Also pay attention to the temperature resistance: V4A withstands up to about 400 °C, which is completely sufficient for hot water pipes.
A common mistake is the use of caps made of mild steel in a damp environment – they rust quickly. Better invest directly in corrosion-resistant stainless steel variants that last for decades. If you need to seal several pipe ends at once or rebuild a system, choosing a set with different sizes is worthwhile. That way you have the right part ready for every situation.
Popular products from the same fitting family
Caps and plugs are often installed together with other threaded fittings. The following three articles show which components you need for a complete installation – from a double nipple as an extension to a reducing socket for size change. Each product is made of the same high-quality V4A steel and fits perfectly into your system.
These three products are representative of the entire range of stainless steel threaded fittings. The double nipple is suitable for coupling two existing fittings; the reducing coupling helps when you need to change from a larger to a smaller diameter. Combine them with matching caps or plugs to completely seal your system.
Frequently asked questions about caps + plugs
What is the difference between a cap and a plug?
A cap (also called a blind plug) has an internal thread and is screwed onto a pipe or a threaded nipple. It seals the end from the outside. A plug, on the other hand, has an external thread and is screwed into a socket or a fitting with internal thread – it seals from the inside. In practice, this means: if you want to seal a pipe end, use a cap. If you want to close an open socket or a tee, use a plug. Both are available in the same materials and sizes.
What thread sizes are common for caps and plugs?
The 224 articles in this category cover almost all common inch sizes – from 1/8 inch to 2 inches and partly larger. Pay attention to the indication 'IG' (internal thread) for caps and 'AG' (external thread) for plugs. Measure the diameter and pitch of your existing connection before purchasing. If unsure, a thread gauge set can help. Most fittings in the plumbing sector use G 1/2, G 3/4 or G 1 inch.
For which media are stainless steel caps and plugs suitable?
Stainless steel 316 (V4A) is resistant to drinking water, hot water up to 90 °C, diluted acids, alkalis, oils, fuels and many chemicals. As a result, the fittings are suitable not only for plumbing and irrigation systems, but also for use in the food industry, solar systems or hydraulic systems. Important: For higher temperatures above 200 °C or extremely aggressive media, you should check the chemical resistance on a case-by-case basis. In the private garden and domestic area, caps and plugs made of V4A cover almost all applications.
How do I seal caps and plugs correctly?
For stainless steel threaded fittings, it is recommended to use Teflon tape (PTFE) or a thread sealing paste. Wrap the tape two to three times evenly in the direction of the thread – not too thin, but also not too thick. Make sure the threads are clean and free of burrs. Tighten the connection hand-tight, do not use excessive torque – otherwise the fitting may be damaged.
More categories for your project
Caps and plugs are just one part of stainless steel threaded fittings. If you are building or extending a complete pipeline, you often need other fittings as well. The Stainless Steel 316 Threaded Fittings Especially for direct connection to pipes or other fittings, the following alternatives are available:
- They are often needed when you want to replace a cap or a plug and instead create a through connection.
- Reducing pieces – for changing from one thread size to a smaller one. Practical when your pipe has a different diameter than the existing connection.
- Union nuts – enable a detachable and tight connection, for example between a hose connection and a threaded fitting. They are the first choice when you need to replace components later.
Before ordering, consider which other fitting types occur in your line. It is often worthwhile to source the entire fitting from one material batch – this supports fit accuracy and uniform corrosion resistance. The mentioned sibling categories complement the caps and plugs perfectly and round off your project.