The VÖLKEL Precision Thread Plug Gauge is your trusted instrument for accurate and quick inspection of G (BSPP) parallel pipe threads in accordance with DIN ISO 228. Designed for use in manufacturing, inspection, and maintenance, it provides a clear GO/NO-GO assessment without complex measuring equipment.
The gauge combines both essential functions: The GO side must screw in easily by hand, confirming the minimum limit. The NO-GO side, marked with a red ring, must not turn more than two complete revolutions. Any deviation means the thread is out of tolerance.
BSP (British Standard Pipe) threads are widely used in hydraulic, pneumatic, and fluid systems. Unlike metric threads with a 60° flank angle, BSPP (G) threads use a 55° Whitworth profile and inch dimensions. They seal on the surface, not the flanks — meaning precision is critical to ensure leak-free fittings. The VÖLKEL plug gauge ensures you maintain that precision with every inspection.
On request, VÖLKEL issues a factory calibration certificate. Calibration is carried out in an independent laboratory, following DIN, ISO, and ANSI standards using IAC thread scanners to ensure traceability and compliance.
| Thread Type | Pipe Thread, G (BSPP) – parallel, 55° Whitworth |
| Nominal Size | G 1.1/8" × 11 tpi |
| Standard | DIN ISO 228 |
| Marking | NO-GO side with red ring |
| Reference Temperature | 20 °C |
| EAN | 4022835165897 |
| Article Number | 16589 |
Can I use this gauge for BSPT (tapered) threads?
No, this gauge is designed for parallel BSPP (G) threads only. BSPT (R) threads require a separate gauge.
How often should it be recalibrated?
Depending on usage, every 12–24 months. More frequently for heavy use or critical applications.
Why the “maximum 2 turns” rule for NO-GO?
It ensures the upper tolerance limit isn’t exceeded — more than two turns indicates an oversize thread.
What if the GO side won’t fit?
The thread is too tight or undersized. Possible causes: incorrect drilling, worn taps, or chip build-up.
How does a G thread seal?
G (BSPP) threads seal on the face using a gasket or O-ring, not on the thread flanks.
Need assistance with selection, testing methods, or a factory calibration certificate? Contact us via our contact form.
| Type of thread | Pipe thread |
|---|---|
| Size | G (BSP) 1.1/8 x 11 |
| EAN | 4022835165897 |
| Item number | 16589 |
| Thread standard | DIN ISO 228 |
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