For plastic pipes and fittings

Our fittings, screwed connections and valves are equipped with Whitworth pipe threads. Dimensions are given in inches, however they do not correspond to the diameter of the thread. In comparison: 25,4 mm is equal to 1 inch, but an outer diameter of 1 inch has a bigger diameter, in this case 33,25 mm. The historical data for standardization in inch, were based on the inner pipe diameter, the wall thicknesses were much bigger. Due to new materials, their properties and further knowledge, the outer diameter was left and the inner diameter varies. Inner and outer diameter do not, comply with the actual inch data. In many cases, the Whitworth thread is indicated as BSP thread.

When using plastic piping systems, a distinction is made between tapered and cylindrical designs of the Whititworth thread.

In order to realize metallically sealed joints, a cylindrical female thread (Rp) and a conical male thread (R) are combined. In case of plastic fittings we would strongly recommend not to tighten with hemp, as this will lead to an increased diameter and the fitting will burst. We would recommend to use teflon tape from a brand manufacturer.

Cylindrical threaded fittings named G are not metallically sealed. In this case you need flat seals or O-rings, as their sealing surfaces are tapered or flat.


DIN ISO 228-1 DIN 2999
external thread
DIN 2999
inner thread
je Inch
Outside diameter
in mm
Core hole diameter
in mm
Pitch diameter
in mm
in mm
thread depth
in mm
G 1/16 R 1/16 Rp 1/16 28 7.72 6.56 7.14 0.91 0.58
G 1/8 R 1/8 Rp 1/8 28 9.73 8.57 9.15 0.91 0.58
G 1/4 R 1/4 Rp 1/4 19 13.16 11.45 12.30 1.34 0.86
G 3/8 R 3/8 Rp 3/8 19 16.66 14.95 15.81 1.34 0.86
G 1/2 R 1/2 Rp 1/2 14 20.96 18.63 19.79 1.81 1.16
G 3/4 R 3/4 Rp 3/4 14 26.44 24.12 25.28 1.81 1.16
G 1 R 1 Rp 1 11 33.25 30.29 31.77 2.31 1.48
G 11/4 R 11/4 Rp 11/4 11 41.91 38.95 40.43 2.31 1.48
G 11/2 R 11/2 Rp 11/2 11 47.80 44.85 46.32 2.31 1.48
G 2 R 2 Rp 2 11 59.61 56.66 58.14 2.31 1.48
G 21/2 R 21/2 Rp 21/2 11 75.18 72.23 73.71 2.31 1.48
G 3 R 3 Rp 3 11 87.88 84.93 86.41 2.31 1.48
G 4 R 4 Rp 4 11 113.03 110.07 111.55 2.31 1.48
All statements without guarantee


Plastic pipe systems

Overview of plastic pipe systems
Technical information on ABS pipe systems
Technical information on PVC  U pipe systems
Technical information on PVC  U transparent pipe systems
Technical information on PVC  C pipe systems
Technical information on PP pipe systems
Technical information on PP-R pipe systems
Technical information on PE pipe systems
Technical information on PVDF pipe systems

Chemiedur - pipe

Technical information on UP-GF (FRP) pipe systems
UP-GF (FRP) pipes
UP-GF (FRP) molded parts and connection
UP-GF-PP (FRP) molded parts and connection
UP-GF (FRP) adhesive collars
UP-GF (FRP) loose flanges
Pot Strainer DN 200 - DN 500 Inliner PP/FRP Coated
Pot Strainer DN 200 - DN 500 Inliner FRP/CBL Coated
Angle Seat Strainer DN 200 - DN 400 Inliner FRP/CBL Coated
Manhole mad of FRP and PP/FRP

Plastic pipes

Calculator for cutting pipes
Guidelines for sawing plastic pipe
Leftovers in plastic pipe
Standardization of plastic pipes and molded parts
PVC U pipes deviations
Pressure loss in pipe systems out of PVC U, PVC C and ABS pipe systems
Distinction between Rp, R and G threads
Screw lengths for flange connections

Plastic fittings

PVC U transparent ball valves
Diaphragm valves
Block valves
Butterfly valves
Plastic needle valves

Plastic Valves according to ATEX

New EU guideline 2014/34/EU
Plastic Valves in EX zones
Y-Strainers PP-EL DN 15 - DN 50
Check valves PP-EL DN 15 - DN 50
Angle seat valves PP-EL DN 15 - DN 50

Bonding of plastic pipes

Bonding manual
Video showing the bonding of pipes

Plastic welding

Guidelines for extrusion welding

Grids / support grids

GFK grids
Grids out of PP -el electrically conductive
Profile support grids out of PP -el electrically conductive

Molded ventilation parts

Ventilation technology

Chemical hose

PVC transparent hose with fabric inlay

Industrial tanks and chemical containers

Dosing tanks and outer containers 35 – 1000 Liter
Salt dissolving tanks 60 -5000 Liter
Storage tanks and vats
Storage tanks for water
Safety and collecting troughs
Industrial tank delivery program
Dosing tanks with agitator
Dosing tank agitators
Dosing tanks with attachments
Dosing tanks made of sheet material
Customized chemical containers
Dosing tanks with level indicators



IBC screw caps DN 150/DN 200
IBC adapters out of PE
IBC adapters out of PP

Attachment parts for tank construction

Vapor separators
CO2 - absorbes
Revision nozzles
Block flange

Filter housings and filter cartridges

PENTEK 3G Slime Line filter housings
PENTEK 3G Standard filter housings
PENTEK Big Blue filter housings
PENTEK PP high temperature filter housings
PENTEK PP all nature filter housings
PENTEK filter bags for Big Blue filter housings
PENTEK surface filter cartridges
PENTEK filter cartridges for depth filtration
PENTEK filter cartridges with activated carbon
CINTROPUR filter systems
CINTROPUR water filters

Flange configurator

Blind flanges, loose flanges,  rectangular flanges

Chemical resistance

Table of chemical resistance for plastic pipe systems

Machined plastic parts

Screw-in parts
Threaded fittings
Screw fittings

Milled plastic parts

Loose flanges and blind flanges made of sheet material

Static mixers

Static mixers made of plastic


Single-type and double-type strainers
Pot strainer DN 300
Angle seat strainer DN 500

Flow meters

Variable area flow meters
Configuration tool for flow meters

Filter presses

Laboratory filter presses

Injection molded parts

Scraper made of PE for filter press