Silicone Reinforced Blanking Cap

-50°C to +250°C 5-12 Bar WP 60mm Long

SRP008K-ASH

£10.69

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Silicone Hose UK

HolmeBank Business Park, Station Road
Unit 5
Mirfield WF14 8NA
United Kingdom

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Tuesday	07:00 – 19:00
Wednesday	07:00 – 18:00
Thursday	07:00 – 18:00
Friday	07:00 – 17:00
Saturday	07:00 – 13:00
Sunday	Closed

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Silicone Reinforced End Cap is a durable, pressure-resistant closure solution designed for automotive, industrial, and marine systems requiring secure sealing of unused outlets, pipes, and connectors. Constructed with a smooth extruded silicone compound inner layer, reinforced by polyester braid, and finished with a high-grade silicone exterior, the cap provides excellent heat stability, flexibility, and resistance to pressure and environmental stress. Built to SAE J20 R3 standards, the reinforced end cap withstands operating temperatures from -50°C to +220°C, with peaks up to +250°C, ensuring long-term reliability in high-performance and demanding environments. Available in a wide range of diameters from 4 mm to 25 mm, each cap features a short 60 mm overall length and 50 mm insertable length, providing a secure and robust seal across different applications.

Key Features:

Inner Layer: Smooth extruded silicone compound for flexibility and sealing integrity.
Reinforcement: Polyester braid for added strength and pressure resistance.
Outer Layer: High-grade silicone offering durability and environmental resistance.
Construction: Multi-ply wall with reinforced structure for long service life.
Operating Temperature: -50°C to +220°C (peak +250°C).
Internal Diameter Range: 4 mm to 25 mm.
Working Pressure: 12 bar (small bore) down to 5 bar (large bore), size dependent.
Bursting Pressure: Typically 3x working pressure (up to 36 bar).
Length: 60 mm overall, 50 mm insertable for secure sealing.
Standard: SAE J20 R3 compliant.

The reinforced silicone end cap combines robust construction with flexibility, ensuring dependable performance in systems handling coolant, oil vapours, air, and industrial fluids. The polyester braid reinforcement stabilises the cap under pressure while maintaining elasticity for easy installation and removal. With smooth internal walls and a reinforced silicone exterior, the cap resists cracking, ozone, and thermal degradation, making it suitable for prolonged use in engine bays, marine machinery, and industrial equipment. Burst ratings up to three times the working pressure provide a strong safety margin, while the compact length ensures neat and efficient sealing of pipe ends, manifolds, and unused outlets.

Applications include sealing off unused coolant or air lines in automotive systems, blanking off turbo and intercooler pipework, protecting connectors during testing and maintenance, and industrial equipment requiring temporary or permanent closure of outlets. Widely used in motorsport, marine engineering, agricultural machinery, and custom fabrication, silicone reinforced end caps deliver reliable protection and containment in high-temperature, medium-pressure environments. Keywords: silicone reinforced end cap, silicone blanking cap, high-temperature sealing cap, SAE J20 R3 silicone cap, industrial hose end cap, reinforced silicone closure.

Specifications

Standard: SAEJ20R3
Wall Thickness: 4mm
Overall Length: 60mm
Insertable Length: 50mm

Size Guide

Inside Diametermm	Outside Diametermm	Working Pressurebar	Bursting Pressurebar	Weightg
4	12	12	36	6
6	14	11	33	10
8	16	11	33	10
10	18	9	27	11
12	20	8	24	15
16	24	7	21	17
18	26	6	18	19
20	28	5	15	20
25	33	5	15	34

Measurements are nominal and may vary slightly.

How to measure ID

Measure the pipe, not the old hose

Heat and age make a used hose swell and go out of round. Take your reading across the metal outlet the hose slides onto — that measurement is your ID.

Use vernier calipers

Set the outer jaws across the widest point of the pipe. A tape measure round a curve reads low by a millimetre or two — enough to buy the wrong size.

Take three readings, keep the largest

Rotate 60° between each. If they disagree the pipe is oval; size to the biggest figure so the hose still seals.

Round to the nearest listed bore

Silicone stretches slightly. If you land between sizes, go down to the smaller bore for a tight seal — never up.

Order by ID, always. Every hose on this site is listed by internal diameter. OD is given for clearance only — it changes with wall thickness and ply count, so it is never the ordering size. On reducers, quote both ends, largest first.

Construction

1 · Outer cover

High-grade silicone

Durability and environmental resistance

2 · Reinforcement

Polyester braid

Added strength and pressure resistance · 12 bar (small bore) down to 5 bar (large bore), size dependent · Typically 3x working pressure (up to 36 bar)

3 · Inner liner

Smooth extruded silicone compound

Flexibility and sealing integrity · -50°C to +220°C (peak +250°C)

Conforms to SAE J20 R3.

Silicone Reinforced Blanking Cap

-50°C to +250°C 5-12 Bar WP 60mm Long

Blank it off. Properly.

Moulded silicone caps that seal on the hose, not on tape.

INTERNAL DIAMETERS

4mm to 25mm

RATED

−50°C to +220°C

WORKING PRESSURE

Up to 12 bar

BUILT TO

SAE J20 R3

Frequently Asked Questions.

Answers to the questions we’re asked most about sizing, fitment and performance.

Still can't find your answer?

What is it for?

Blanking off a pipe stub, hose tail or port you are not using - deleting a redundant takeoff after an engine swap, capping an unused water or vacuum port, or protecting open pipe ends during storage, transport, painting or blasting.

What size do I need?

Measure the outside diameter of the pipe stub you are blanking and choose the cap with the matching internal diameter. It should be a firm push fit that needs some effort, not a loose slide. Available in internal diameters from 4mm to 25mm, in black and blue.

Can I use it on a pressurised port?

Yes - this is the reinforced version, with polyester braid and a working pressure rating, which is what you want on a pressurised coolant or boost port.

What temperature will it take?

-50C to +250C, built to SAE J20 R3. That covers coolant service and general engine bay temperatures comfortably.

Do I need a clip as well?

On a zero-pressure stub the interference fit is usually enough. On anything pressurised, always fit a clip - a stainless worm drive clip on coolant, a T-bolt on boost. Position it over the section of cap supported by the stub underneath, not out at the closed end.

Can I use it on a fuel or oil port?

No - this is standard silicone and will swell and degrade in contact with hydrocarbons. Blanking a fuel or oil port needs a fluorosilicone or nitrile cap, or a metal blanking plug. Tell us the port and what it carried and we will point you at something suitable.