BSPP Pipe Thread vs. Garden Hose Thread
Comparing 2 standards across 10 specifications. 10 key differences identified.
BSPP (British Standard Pipe Parallel), designated with the prefix 'G' under ISO 228-1, is a straight cylindrical pipe thread with a 55° Whitworth rounded crest and root profile. Unlike tapered threads, BSPP threads do not seal along the thread flanks, requiring an external bonded elastomeric washer (Dowty seal), O-ring, or copper crush washer on a flat mating shoulder.
Garden Hose Thread (GHT) is the standardized North American outdoor water coupling governed by ANSI/ASME B1.20.7. Specified as 3/4"-11.5 NH, it features a straight, non-tapered thread with a 1.0625-inch (27.0 mm) major diameter that seals via axial compression against a flat rubber washer inside the female swivel coupling.
Specification Comparison Table
10 Parameters| Parameter / Spec | ||
|---|---|---|
|
Standard Governing Body
|
ISO 228-1 / BS 2779 / DIN ISO 228 | ANSI / ASME B1.20.7 |
|
Thread Designation
|
G (e.g., G 1/2", G 3/4") | 3/4"-11.5 NH (National Hose) |
|
Thread Form & Flank Angle
|
55° Whitworth with radiused crests and roots | 60° American National straight parallel thread |
|
Sealing Mechanism
|
Bonded seal (Dowty washer), O-ring, or elastomeric gasket on shoulder | Flat elastomeric washer compressed in female swivel seat |
|
Taper
|
None (0° — straight cylindrical thread) | — |
|
Common Pitches (TPI)
|
G 1/8": 28 TPI | G 1/4"-3/8": 19 TPI | G 1/2"-3/4": 14 TPI | G 1"-2": 11 TPI | — |
|
Primary Geographical Region
|
Europe, UK, Australia, Asia, and global industrial hydraulics | — |
|
Major Diameter (Male Outer ø)
|
— | 1.0625 inches (27.0 mm) |
|
Thread Pitch / TPI
|
— | 11.5 TPI (2.209 mm pitch) |
|
Operating Water Pressure
|
— | 40–80 PSI typical residential (up to 150 PSI burst) |