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General Technical Information (Hydraulic Seals)

General technical information for hydraulic seals covers the fundamental parameters that influence seal performance: operating pressure (peak and continuous), fluid type and viscosity, operating temperature range, sliding speed, rod and bore surface finish, and hardware tolerances. SKF provides design guidelines for seal housing grooves, including dimensions, surface finishes, and lead-in chamfers. Information on extrusion gaps, permissible gap size relative to pressure and seal material hardness, and back-up ring application is included. Understanding these technical fundamentals ensures that the selected seal cross-section, material, and groove design are fully compatible, preventing failure modes like spiral twist, extrusion damage, and fluid bypass.

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JSW Steel – industrial client of Drishti Powertech
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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 Calculation

Maximum gap based on pressure, temperature, and seal material hardness.

Groove Design Standards

ISO 5597, ISO 6195, and SKF‑specific recommendations.

Surface Finish Requirements

Rod and bore Ra, Rz, and material ratio (Rmr) guidance.

Lead‑In Chamfers

Angles and lengths to prevent seal damage during assembly.

Back‑Up Ring Application

When and how to use to extend pressure capability.

Thermal Expansion Margins

Groove dimensions adjusted for operating temperature.

Preventing Spiral Twist Failure in Rod Seals

If the seal groove is not square to the rod axis, the seal can twist into a figure‑eight shape and leak catastrophically. SKF’s technical information specifies the maximum permissible angular deviation of the groove face — a tiny but critical tolerance that many general machining drawings miss.

SKF product
SKF application

Sizing an Extrusion Gap for a 400 Bar Cylinder

At 400 bar, a 70 Shore A NBR seal will extrude into a gap larger than 0.2 mm and fail. SKF’s technical data provides a chart: for that pressure and seal hardness, the gap must be ≤0.15 mm, or a PTFE back‑up ring must be added. This chart is an essential tool for cylinder design engineers.