SKF products

SKF

ST08-13 Customized Machined Back-Up Rings

The ST08-13 programme from SKF provides machined back-up rings in custom sizes for hydraulic and pneumatic sealing systems. These anti-extrusion rings are machined from PTFE, polyamide, or PEEK stock to the exact ID, OD, and thickness required. They are used in conjunction with O-rings and other elastomeric seals to bridge the extrusion gap and allow higher pressure operation in non-standard cylinder and valve configurations. The ability to manufacture single or small quantities without tooling is invaluable for prototype development, special test rigs, and legacy equipment maintenance. SKF’s machined back-up rings are produced with precise axial thickness and flatness to ensure even load distribution and effective extrusion prevention, extending the pressure rating and life of the associated soft seals.

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Trusted by Industry Leaders

SAIL – Steel Authority of India Limited, industrial client of Drishti Powertech
Tata Steel – industrial client of Drishti Powertech
Hindalco – Aditya Birla Group aluminium & copper, industrial client of Drishti Powertech
Jindal Steel & Power – industrial client of Drishti Powertech
NMDC – National Mineral Development Corporation, industrial client of Drishti Powertech
JSW Steel – industrial client of Drishti Powertech
Vedanta ESL Steel Limited – industrial client of Drishti Powertech
NALCO – National Aluminium Company Limited, industrial client of Drishti Powertech
Industrial enterprise – client of Drishti Powertech LLP
Hindustan Copper Limited – Govt. of India enterprise, industrial client of Drishti Powertech
UltraTech Cement – industrial client of Drishti Powertech
Coal India Limited – industrial client of Drishti Powertech
ACC Cement – industrial client of Drishti Powertech
Indian Oil Corporation – industrial client of Drishti Powertech
SAIL – Steel Authority of India Limited, industrial client of Drishti Powertech
Tata Steel – industrial client of Drishti Powertech
Hindalco – Aditya Birla Group aluminium & copper, industrial client of Drishti Powertech
Jindal Steel & Power – industrial client of Drishti Powertech
NMDC – National Mineral Development Corporation, industrial client of Drishti Powertech
JSW Steel – industrial client of Drishti Powertech
Vedanta ESL Steel Limited – industrial client of Drishti Powertech
NALCO – National Aluminium Company Limited, industrial client of Drishti Powertech
Industrial enterprise – client of Drishti Powertech LLP
Hindustan Copper Limited – Govt. of India enterprise, industrial client of Drishti Powertech
UltraTech Cement – industrial client of Drishti Powertech
Coal India Limited – industrial client of Drishti Powertech
ACC Cement – industrial client of Drishti Powertech
Indian Oil Corporation – industrial client of Drishti Powertech
ONGC – Oil and Natural Gas Corporation, industrial client of Drishti Powertech
GAIL India Limited – industrial client of Drishti Powertech
NTPC – National Thermal Power Corporation, industrial client of Drishti Powertech
Tata Power – industrial client of Drishti Powertech
Indian Railways – industrial client of Drishti Powertech
IFFCO – Indian Farmers Fertiliser Cooperative, industrial client of Drishti Powertech
Super Smelters Limited – industrial client of Drishti Powertech
Rashmi Group – industrial client of Drishti Powertech
Shyam Steel – industrial client of Drishti Powertech
S R Rungta Group – industrial client of Drishti Powertech
MP Birla Group – industrial client of Drishti Powertech
Usha Martin – industrial client of Drishti Powertech
Shyam Metalics – industrial client of Drishti Powertech
Nuvoco Vistas Corporation – industrial client of Drishti Powertech
ONGC – Oil and Natural Gas Corporation, industrial client of Drishti Powertech
GAIL India Limited – industrial client of Drishti Powertech
NTPC – National Thermal Power Corporation, industrial client of Drishti Powertech
Tata Power – industrial client of Drishti Powertech
Indian Railways – industrial client of Drishti Powertech
IFFCO – Indian Farmers Fertiliser Cooperative, industrial client of Drishti Powertech
Super Smelters Limited – industrial client of Drishti Powertech
Rashmi Group – industrial client of Drishti Powertech
Shyam Steel – industrial client of Drishti Powertech
S R Rungta Group – industrial client of Drishti Powertech
MP Birla Group – industrial client of Drishti Powertech
Usha Martin – industrial client of Drishti Powertech
Shyam Metalics – industrial client of Drishti Powertech
Nuvoco Vistas Corporation – industrial client of Drishti Powertech

Extrusion Gap Bridging

Prevents O‑ring damage in high‑pressure glands.

PTFE, PEEK, and PA Materials

For different pressure and temperature ranges.

Scarf‑Cut, Step‑Cut, and Solid Designs

Matched to installation method.

Customised Thickness and Diameter

Fits non‑standard O‑rings and clearance gaps.

Chemical Compatibility

Material chosen for the hydraulic fluid and environment.

Prototyping without Tooling

Enables rapid design iterations for new cylinder developments.

Why a Scarf‑Cut Back‑Up Ring Is Preferred for On‑Line Replacement

A scarf‑cut ring can be opened and slipped over the piston without removing the piston from the rod. In a cylinder rebuild, this saves disassembly time. SKF machines the precise spiral cut so that when assembled, there is no gap for the O‑ring to extrude through.

SKF product
SKF application

PEEK Back‑Up Rings for 300°C Steam Valves

In a steam turbine control valve, the O‑ring gland temperature reached 280°C. PTFE would soften and extrude. SKF machined PEEK back‑up rings, which maintained their strength at that temperature, protecting the FKM O‑rings and enabling a leak‑free valve stem seal for the turbine’s service life.