Short answer
Permeation is the ability of a fluid to pass through the hose material at the molecular level. It is not the same mechanism as a visible hole or a connection leak. For gases, volatile or hazardous fluids, it must be addressed in addition to the chemical resistance assessment.
Technical explanation
An inner tube showing no significant chemical degradation does not mean there is no fluid passage at all. Permeation is assessed depending on the fluid type, material and operating conditions. Consequences such as accumulation under the reinforcement or outer layer and release into the surrounding environment in an enclosed space are examined per service. Some products may have special construction or cover treatments from the manufacturer; these do not permit actions such as randomly piercing holes in the field. The product design must not be tampered with without authorization.
Topic-specific checkpoints
| Item | Description |
|---|---|
| Mechanism | Passage through the material; different from a hole or a loose connection. |
| Inputs | Fluid, inner tube, temperature and pressure. |
| Environment | Enclosed space, ventilation and assessment of hazardous accumulation. |
| Evidence | Manufacturer data specific to the product and condition; a general material name is not sufficient. |
How is it assessed in practice?
In a complaint of odor or surface blistering, do not see tightening the connection alone as the solution. Record the fluid, temperature, pressure and the condition in which the problem occurs; follow the safe operating procedure. For example, if gas service is being considered in an enclosed equipment space, add the environment assessment to the hose selection file as well. Read the chemical table notes separately and request a manufacturer statement on permeation for the specific product.
Original editorial recommendation; not a clause of a standard.
Frequently asked questions
If there is a blister on the outer cover, can I remove it by piercing it myself?
No. The cause of the blister and the condition of the product must be assessed through an authorized inspection. Random piercing does not turn damage into a safe product design.
Source coverage
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S017
Parker Safety Guide, Publication 4400-B.1 Parker Hannifin · accessed 2026-10-20 PDF page 2; 2.5 Fluid CompatibilityPDF page 2; 2.5 Fluid Compatibility | PDF page 2; 2.6 PermeationPDF page 4; 5.1 Maintenance Programme, 5.2 Visual Inspection, 5.3 Other Inspection and 5.6 Hose Inspection and Failure | PDF page 2; 2.9 Environment
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S020
Chemical Resistance Chart Gates · accessed 2026-10-19 PDF page 2 / printed page 1: Chemical Resistance Table, notes
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S024
Hose and Flexible Tubing, MS-01-180 Swagelok · accessed 2026-10-19 PDF pages 4–5 / printed 253–254: Nomenclature; pages 8–9: selection, installation and use