Pipe & Pneumatic Fittings · ISO 228 (G)

ISO 228 (G) BSP Pipe Thread Fittings Dimensions

Specification summary of ISO 228 (G) as applied to bsp pipe thread fittings: the dimensions the standard controls, the tolerance and product grades it defines, the full specified size range, and the equivalent DIN/ISO/ASME designations.

ISO 228 (G) — Scope

ISO 228 (G) specifies the dimensions and tolerances of bsp pipe thread fittings. Material, property class, surface finish and packaging are governed by separate documents in the same standards family (for example ISO 898-1 for the mechanical property classes of bolts and screws).

Tolerance & Product Grades

ISO 228 (G), alongside the related ISO 228 (G) entries on this site, specifies product grades (typically A or B for fine work and C for general engineering) and tolerance classes for the controlling dimensions. Choose the grade against the precision your application requires.

Dimensions Specified by ISO 228 (G)

Size	Nominal size (in)	Major diameter (mm)	Pitch (mm)	Threads per inch (TPI)	Tap drill (mm)	Reference standard	Notes
G1/16	1/16	7.723	0.907	28	6.8	ISO 228-1 / DIN ISO 228	Parallel pipe thread (G), sealed by gasket
G1/8	1/8	9.728	0.907	28	8.8	ISO 228-1 / DIN ISO 228	Parallel pipe thread (G), sealed by gasket
G1/4	1/4	13.157	1.337	19	11.5	ISO 228-1 / DIN ISO 228	Parallel pipe thread (G), sealed by gasket
G3/8	3/8	16.662	1.337	19	15.0	ISO 228-1 / DIN ISO 228	Parallel pipe thread (G), sealed by gasket
G1/2	1/2	20.955	1.814	14	18.5	ISO 228-1 / DIN ISO 228	Parallel pipe thread (G), sealed by gasket
G5/8	5/8	22.911	1.814	14	20.5	ISO 228-1 / DIN ISO 228	Parallel pipe thread (G), sealed by gasket
G3/4	3/4	26.441	1.814	14	24.0	ISO 228-1 / DIN ISO 228	Parallel pipe thread (G), sealed by gasket
G7/8	7/8	30.201	1.814	14	27.5	ISO 228-1 / DIN ISO 228	Parallel pipe thread (G), sealed by gasket
G1	1	33.249	2.309	11	30.5	ISO 228-1 / DIN ISO 228	Parallel pipe thread (G), sealed by gasket
G1-1/8	1-1/8	37.897	2.309	11	35.0	ISO 228-1 / DIN ISO 228	Parallel pipe thread (G), sealed by gasket
G1-1/4	1-1/4	41.91	2.309	11	39.0	ISO 228-1 / DIN ISO 228	Parallel pipe thread (G), sealed by gasket
G1-1/2	1-1/2	47.803	2.309	11	45.0	ISO 228-1 / DIN ISO 228	Parallel pipe thread (G), sealed by gasket
G1-3/4	1-3/4	53.746	2.309	11	51.0	ISO 228-1 / DIN ISO 228	Parallel pipe thread (G), sealed by gasket
G2	2	59.614	2.309	11	57.0	ISO 228-1 / DIN ISO 228	Parallel pipe thread (G), sealed by gasket
G2-1/4	2-1/4	65.71	2.309	11	63.0	ISO 228-1 / DIN ISO 228	Parallel pipe thread (G), sealed by gasket
G2-1/2	2-1/2	75.184	2.309	11	72.0	ISO 228-1 / DIN ISO 228	Parallel pipe thread (G), sealed by gasket
G2-3/4	2-3/4	81.534	2.309	11	79.0	ISO 228-1 / DIN ISO 228	Parallel pipe thread (G), sealed by gasket
G3	3	87.884	2.309	11	85.0	ISO 228-1 / DIN ISO 228	Parallel pipe thread (G), sealed by gasket
G3-1/2	3-1/2	100.33	2.309	11	97.5	ISO 228-1 / DIN ISO 228	Parallel pipe thread (G), sealed by gasket
G4	4	113.03	2.309	11	110.0	ISO 228-1 / DIN ISO 228	Parallel pipe thread (G), sealed by gasket
G5	5	138.43	2.309	11	135.0	ISO 228-1 / DIN ISO 228	Parallel pipe thread (G), sealed by gasket
G6	6	163.83	2.309	11	160.0	ISO 228-1 / DIN ISO 228	Parallel pipe thread (G), sealed by gasket

Equivalent Standards

Where direct equivalents exist (ISO ↔ DIN, ISO ↔ ASME), they are listed on the parent BSP Pipe Thread Fittings page. Always confirm against the dimensions on this page, since some "equivalent" standards differ in tolerances and head geometry.

Companion Standards

ISO 228 (G) controls only the geometry of bsp pipe thread fittings. The mechanical strength is set by ISO 898-1 (bolts and screws) or ISO 898-2 (nuts); the surface finish is governed by separate finish standards (e.g. ISO 4042 for electroplating). For corrosion testing, the relevant document is ISO 9227 (neutral salt spray).

Technical Drawing

Customize the parameters below — every spec field is editable, and the drawing redraws to match the values you choose. Changing the size will snap the other fields to that size's standard values; you can then override any individual value.

Sends the selected values to the quote form below.

Request a Quote

Adjust the parameters in the drawing above and click "Request this configuration" to send the exact specification straight to this form.

Category Type Standard Thread size Material Finish

Dimensions & Specifications (ISO 228 (G))

Size	Nominal size (in)	Major diameter (mm)	Pitch (mm)	Threads per inch (TPI)	Tap drill (mm)	Reference standard	Notes
G1/16	1/16	7.723	0.907	28	6.8	ISO 228-1 / DIN ISO 228	Parallel pipe thread (G), sealed by gasket
G1/8	1/8	9.728	0.907	28	8.8	ISO 228-1 / DIN ISO 228	Parallel pipe thread (G), sealed by gasket
G1/4	1/4	13.157	1.337	19	11.5	ISO 228-1 / DIN ISO 228	Parallel pipe thread (G), sealed by gasket
G3/8	3/8	16.662	1.337	19	15.0	ISO 228-1 / DIN ISO 228	Parallel pipe thread (G), sealed by gasket
G1/2	1/2	20.955	1.814	14	18.5	ISO 228-1 / DIN ISO 228	Parallel pipe thread (G), sealed by gasket
G5/8	5/8	22.911	1.814	14	20.5	ISO 228-1 / DIN ISO 228	Parallel pipe thread (G), sealed by gasket
G3/4	3/4	26.441	1.814	14	24.0	ISO 228-1 / DIN ISO 228	Parallel pipe thread (G), sealed by gasket
G7/8	7/8	30.201	1.814	14	27.5	ISO 228-1 / DIN ISO 228	Parallel pipe thread (G), sealed by gasket
G1	1	33.249	2.309	11	30.5	ISO 228-1 / DIN ISO 228	Parallel pipe thread (G), sealed by gasket
G1-1/8	1-1/8	37.897	2.309	11	35.0	ISO 228-1 / DIN ISO 228	Parallel pipe thread (G), sealed by gasket
G1-1/4	1-1/4	41.91	2.309	11	39.0	ISO 228-1 / DIN ISO 228	Parallel pipe thread (G), sealed by gasket
G1-1/2	1-1/2	47.803	2.309	11	45.0	ISO 228-1 / DIN ISO 228	Parallel pipe thread (G), sealed by gasket
G1-3/4	1-3/4	53.746	2.309	11	51.0	ISO 228-1 / DIN ISO 228	Parallel pipe thread (G), sealed by gasket
G2	2	59.614	2.309	11	57.0	ISO 228-1 / DIN ISO 228	Parallel pipe thread (G), sealed by gasket
G2-1/4	2-1/4	65.71	2.309	11	63.0	ISO 228-1 / DIN ISO 228	Parallel pipe thread (G), sealed by gasket
G2-1/2	2-1/2	75.184	2.309	11	72.0	ISO 228-1 / DIN ISO 228	Parallel pipe thread (G), sealed by gasket
G2-3/4	2-3/4	81.534	2.309	11	79.0	ISO 228-1 / DIN ISO 228	Parallel pipe thread (G), sealed by gasket
G3	3	87.884	2.309	11	85.0	ISO 228-1 / DIN ISO 228	Parallel pipe thread (G), sealed by gasket
G3-1/2	3-1/2	100.33	2.309	11	97.5	ISO 228-1 / DIN ISO 228	Parallel pipe thread (G), sealed by gasket
G4	4	113.03	2.309	11	110.0	ISO 228-1 / DIN ISO 228	Parallel pipe thread (G), sealed by gasket
G5	5	138.43	2.309	11	135.0	ISO 228-1 / DIN ISO 228	Parallel pipe thread (G), sealed by gasket
G6	6	163.83	2.309	11	160.0	ISO 228-1 / DIN ISO 228	Parallel pipe thread (G), sealed by gasket

Frequently Asked Questions

Can I substitute ISO 228 (G) for the corresponding DIN standard on a drawing?

On modern drawings the ISO standard is the master reference; the older DIN equivalent is a cross-reference. For most dimensional purposes the parts are interchangeable, but check tolerance grades and the head height — these are the most common points of divergence.

When did ISO 228 (G) last revise its dimensional table?

ISO standards for bsp pipe thread fittings are reviewed on roughly a five-year cycle. Always reference the latest published edition (or the edition cited contractually); the dimensional table on this page reflects the current commercially-supplied form.

What does ISO 228 (G) specify for BSP Pipe Thread Fittings?

ISO 228 (G) specifies the dimensions and tolerances of bsp pipe thread fittings. Material and property class are governed by separate standards in the same family.

What product grades does ISO 228 (G) define?

ISO 228 (G) typically distinguishes product grades for precision (A/B) and general engineering (C). The selection for BSP Pipe Thread Fittings depends on the precision your application requires.

How do I request a quotation?

Use the technical drawing on this page to pick the exact configuration, then submit it with the quote form. We respond within one business day.