What is a Stainless Steel Fitting?

Find out why stainless-steel fittings are ideally suited for food and beverage – and how to choose the right one for your application.

What is a Stainless Steel Fitting?

A stainless steel fitting, as the name suggests, is made from a form of stainless steel; most are made from 316L, this being the second most common austenitic stainless steel after 304. The addition of molybdenum to 316 gives greater corrosion resistance, compared to 304. The ‘L’ refers to a low carbon version.

How do stainless steel fittings work?

Here, we will focus on push-in fittings; their construction is shown in the above diagram, which shows a push-in to threaded fitting. The tube is held by a grab ring (4) and the seal is assisted by the ‘O’ ring (6). It should be noted that the fittings are for use with plastic tubing.

It is important to make sure that the end of the tube is cut square. It is then pushed all the way into the fitting body until it hits the stop. The tube is pulled back slightly to make sure the grab ring is ‘engaged’ and a pressure proof seal is created. To release, the release sleeve (2) is depressed and the tube withdrawn.

How do I select a stainless steel fitting?

Tubing and pneumatic fittings should be designed to allow the necessary flow without introducing significant pressure drops; as a rule, keeping the pipework as simple as possible will reduce energy loss though the system - for example don't use elbows if straight runs are possible. The following should be considered in choosing the correct fitting type:

• working pressure – the fittings themselves will operate from vacuum to 15 bar, but the tubing (and temperature, see below) may limit this value

• working temperature - increasing temperature will reduce the operating pressure of nylon and polyurethane tubing; the working temperature of the fittings is -150C to +2250C

• working environment - both possible contaminants and ease of access for construction and maintenance. Stainless steel is naturally resistant to aggressive environments

• construction and maintenance - any approvals required for the application, for example, use in the Food Industry.

Types of stainless steel fitting?

All standard shapes are available to complete a system design:

• variety of straight adaptors and connectors

• bulkhead connector

• variety of elbow connectors

• variety of tee connectors

• accessories

All work on the mechanical principle of connection outlined above.

Typical applications for a stainless steel fitting?

Stainless steel fittings are ideally suited to applications where the working environment can be hostile – for example, hot with aggressive chemicals. The Food & Beverage sector is a regular user of stainless steel, due to the often caustic wash-down procedures.

Do I need anything else for a stainless steel fitting?

Tubing will be required and this will need to be suited to the working environment, particularly as the fittings are only suited to plastic tubing. If the fitting is part of a new build then components such as air preparation, valves and actuators may be required.

Visit our Fittings section to find out more.