Stainless Steel Threaded Fittings

Stainless Steel Threaded Reducers

A stainless reducing bush is an AISI 304 fitting with a male-threaded large end and a female-threaded small end that reduces the size at the port of a stainless fitting or equipment.

It is used to connect instruments to process equipment ports, to reduce tee branches and for transitions to dosing lines. 40 size combinations from 1/4″ × 1/8″ to 4″ × 3″ are available.

40 sizescombinations (product range)

4″ × 3″largest size

R + Rpmale and female ends

20 barat −20 … +38 °C (ISO 4144)

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Main Applications

Instrument connections to tank and reactor ports
Reducing stainless tee and cross branches
Transitions to dosing pump and injection lines
Pressure gauge and sensor fittings (1/4″ – 1/2″)
Small-bore pipe to pump and filter ports
Sampling points in food lines

Technical Data

Fitting type	Reducing bush (male-female)
Product standard	ISO 4144 (manufacturer sheet)
Material	AISI 304 stainless steel (product range)
Thread	Large end ISO 7-1 R male, small end Rp female thread
Size range	1/4″ × 1/8″ – 4″ × 3″ (product range)
Example sizes	1/2″ × 1/4″, 3/4″ × 1/2″, 1 1/2″ × 1″, 3″ × 2″ (product range)
Number of sizes	40 combinations (product range)
Pressure, −20 … +38 °C	20 bar (ISO 4144 Table 2, manufacturer sheet)
Pressure, 100 °C	16.5 bar (ISO 4144 Table 2, manufacturer sheet)
Pressure, 150 °C	15 bar (ISO 4144 Table 2, manufacturer sheet)
Female-female transition	With a stainless socket plus reducing bush
Surface	Stainless, uncoated

Material Options

Part	AISI 304 stainless	AISI 316 stainless	Galvanized malleable iron
Body	AISI 304, cast or bar depending on model	AISI 316, depending on model	Malleable iron EN-GJMB-350-10, galvanized
Surface	Uncoated stainless	Uncoated stainless	Zinc coated
Thread	R male + Rp female	R male + Rp female	R male + Rp female
Pressure rating	20 bar −20…+38 °C (ISO 4144)	20 bar −20…+38 °C (ISO 4144)	25 bar −20…120 °C (EN 10242)
Suitable media	Food, drinking water, mild chemicals	Chloride-containing water, seawater, aggressive chemicals	Cold domestic water, fire water

Which material? A reducing bush should be chosen in the same grade as the stainless port it goes into; use a 316 bush on a 316 tank or valve.

Advantages

Widest Size Choice

40 combinations from 1/8″ to 4″

Suited to Instruments

Instruments connect directly to small-bore ports

No Intermediate Piece

Screws into the port, no socket or nipple needed

Stainless Integrity

Same material as the equipment port

Construction and Design Features

ISO 7-1 R taper male thread on the large end, Rp female thread on the small end
Body with hexagonal wrench head (depending on model)
Uncoated stainless surface
ISO 4144 pressure ratings

Send the male large and female small size and the quantity; we will confirm the suitable bush among 40 sizes.

How to Choose?

Measure the port sizeDetermine the female thread size of the port the bush will screw into.
Determine the instrument sizeMeasure the male thread size of the instrument or pipe at the small end.
Write the sizeUse the order large × small when ordering.
Match the gradeIf the port is 316, choose a 316 bush as well.