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BS EN ISO 11116 — Gas Cylinders — 17E Taper Thread for Connection of Valves
Gas cylinders — 17E taper thread for connection of valves — Part 1: Specifications; Part 2: Thread gauges
🔩 BS EN ISO 11116 specifies the 17E taper thread used for connecting valves to transportable gas cylinders, an important basis for standardising cylinder-valve connections. The series has two parts: BS EN ISO 11116-1 specifies the thread specifications (dimensions, tolerances and verification), and BS EN ISO 11116-2 specifies the thread gauges used to verify the thread. The 17E taper thread achieves sealing and reliable connection through the taper fit, and is widely used for industrial, medical and special-gas cylinder valves.
💡 The taper thread forms a tight metal-to-metal or thread sealing surface after tightening, able to withstand the high-pressure gas inside the cylinder without leakage — a critical interface for cylinder-valve connection. Its dimensions and tolerances must be strictly controlled, otherwise sealing failure or even valve blow-off can occur.
1. Series Overview and Scope 📌
In the UK this series is the responsibility of subcommittee PVE/3/1 (Valve fittings for gas cylinders), within the ISO/TC 58 “Gas cylinders” system. BS EN ISO 11116-1:1999 is identical to ISO 11116-1:1999, was approved by CEN in April 1999, and published as a British Standard on 15 July 1999 (© BSI 04-2000). BS EN ISO 11116-2:1999 specifies the corresponding thread gauges; its text has been compiled from a scanned version, so the official published version should be taken as authoritative.
| Part | Subject | ICS | ISO Equivalent | Core Content |
|---|---|---|---|---|
| BS EN ISO 11116-1:1999 | Thread specifications | 21.040.30; 23.060.40 | ISO 11116-1:1999 | Dimensions, tolerances and verification of the 17E taper thread |
| BS EN ISO 11116-2:1999 | Thread gauges | 23.020.30 | ISO 11116-2:1999 | Thread gauges for verifying the 17E taper thread |
⚠️ This series applies to the 17E taper thread for connecting valves to transportable gas cylinders. For other thread types (e.g., parallel or pipe threads) or other taper-thread sizes, refer to the relevant standards.
2. Thread Specifications (Part 1) 🔧
BS EN ISO 11116-1 specifies the basic dimensions, tolerances and verification of the 17E taper thread. The Standard gives the pitch, taper, pitch diameter, major and minor diameters, thread angle, thread length and other key dimensions with tolerances, plus the surface quality and verification method.
The sealing of the taper thread depends on the taper fit and thread-form accuracy. The Standard requires a reliable seal over the specified engagement length, complete thread form free of burrs and cracks, and satisfactory surface finish. It also specifies the verification gauges and methods so that threads made by cylinder and valve manufacturers are mutually compatible.
3. Thread Gauges (Part 2) 🔩
BS EN ISO 11116-2 specifies the thread gauges (plug and ring gauges) used to verify the 17E taper thread. Gauges control the thread dimensions and tolerances during manufacture and inspection, ensuring interchangeability and sealing between the cylinder-neck thread and the valve thread. The Standard specifies the thread form, dimensions, tolerances, material and calibration of the gauges.
Thread gauges have GO and NOT-GO ends, used to check the acceptable limits of the thread. When using gauges on a taper thread, judgement should be made at the specified engagement depth or gauge plane to ensure correct results.
💡 Part 2 covers the specific dimensions and calibration requirements of thread gauges; this overview is compiled from general domain knowledge — refer to the official BSI publication for the actual values and judgement rules.
| Comparison | Thread Specifications (Part 1) | Thread Gauges (Part 2) |
|---|---|---|
| Main object | The 17E taper thread itself | Gauges used to verify the thread |
| Key content | Dimensions, tolerances, thread form, verification | Gauge form, tolerances, material, calibration |
| Purpose | Define the acceptance requirements of the thread | Ensure consistency and interchangeability of manufactured threads |
| Users | Cylinder/valve manufacturers | Manufacturers, inspection bodies |
4. Dimensions, Tolerances and Verification Requirements 🛠️
The dimensions and tolerances of the 17E taper thread are central to the safety of the cylinder-valve connection. The Standard gives explicit values for pitch, taper, pitch diameter, thread angle and engagement length, with corresponding verification methods. During manufacture, suitable thread gauges should be used to verify that the thread dimensions meet the requirements.
- Taper: the taper provides sealing; taper deviation directly affects seal performance.
- Pitch diameter and tolerance: the pitch diameter is a key mating dimension and must be tightly controlled.
- Thread form and surface: the form should be complete, free of burrs, cracks and visible defects.
- Verification: use gauges at the gauge plane for GO/NOT-GO checks.
5. Engineering Application Practice 🌐
The 17E taper thread is widely used in valve connections of industrial, medical, welding and special-gas cylinders. Cylinder fillers, valve manufacturers and inspection bodies use this series for product inspection and acceptance. In periodic cylinder inspection, wear, corrosion and damage of the neck thread are key check items; repair or replacement should be carried out where necessary to ensure filling and use safety.
🚨 Cylinders hold high-pressure gas (often 150 bar or more); failure of the neck thread can lead to valve blow-off, gas leakage or even explosion. Strictly comply with the Standard’s dimension and verification requirements and never use worn, damaged or non-conforming valves and threads.
6. Frequently Asked Questions ❓
❓ Q: Why do cylinder valves use a taper thread?
A: The taper thread forms a tight seal after tightening through the taper fit, withstanding high-pressure gas without leakage; it is also self-locking and resistant to loosening, suiting the high-pressure, frequent-filling service of cylinders.
A: The taper thread forms a tight seal after tightening through the taper fit, withstanding high-pressure gas without leakage; it is also self-locking and resistant to loosening, suiting the high-pressure, frequent-filling service of cylinders.
❓ Q: What is the role of the thread gauge?
A: Thread gauges (plug/ring) verify the thread dimensions and tolerances, ensuring interchangeability and sealing between the cylinder neck and the valve. GO passes and NOT-GO stops indicate the thread is within tolerance.
A: Thread gauges (plug/ring) verify the thread dimensions and tolerances, ensuring interchangeability and sealing between the cylinder neck and the valve. GO passes and NOT-GO stops indicate the thread is within tolerance.
❓ Q: How is a neck thread judged acceptable?
A: Verify with standard gauges at the specified gauge plane, and visually inspect for complete thread form and any burrs, cracks, corrosion or damage; if abnormal, stop use and rectify.
A: Verify with standard gauges at the specified gauge plane, and visually inspect for complete thread form and any burrs, cracks, corrosion or damage; if abnormal, stop use and rectify.
❓ Q: Which cylinders does this series apply to?
A: Transportable gas cylinders using the 17E taper thread for valve connection, including industrial, medical and special-gas cylinders. The exact scope and cylinder sizes are per the standard text.
A: Transportable gas cylinders using the 17E taper thread for valve connection, including industrial, medical and special-gas cylinders. The exact scope and cylinder sizes are per the standard text.