Joining without welding
Compression fittings for steel pipe and boiler tube
A pipe end without thread, no welding allowed, the line has to run again today: the malleable-iron compression fitting has sat on exactly this problem since 1936. A grip ring grabs the plain pipe, a seal ring takes over the sealing, the cone nut tensions both – resistant to tension and shear, up to 3° deflection, mounted with standard tools. This page says which series belongs to which pipe and medium, where the service limits are and what of it we stock.
- Pipe types
- Threaded pipe EN 10255 / EN 10220 series 1 (17.2–114.3 mm) · boiler tube EN 10220 series 2/3 (20–108 mm)
- Types
- A/AF male thread · I/IF female thread · O/OF coupling (also reduced, long) · T/TF tee · W elbow · EK end cap · F = flange version from 2 1/2 inch
- Materials
- Malleable iron hot-dip galvanised (Gebo EN-GJMB-350-10, GF EN-GJMW-400-5) · lead-free brass · seal NBR, EPDM or NBR + graphite (HTB)
- Manufacturers
- Gebo gebooriginal, gebomessing, minigebo · GF PRIMOFIT, FIREJOINT
Which series for which pipe and medium
The series decides pipe, seal and approval. For threaded pipe and water, gas outside buildings, compressed air or heating-oil filling lines it is series 150 (up to 2 inch) and 220 (2 1/2 to 4 inch) with NBR seal. For drinking water the same bodies with EPDM as 151 and 222 – or the EPDM moulded rings for retrofitting, which we stock. For boiler tube (black pipe to EN 10220 series 2 and 3, 20 to 108 mm) the series 15S and 22S. For gas inside buildings the HTB series 180 (up to 2 inch, max. 5 bar) and 225 (2 1/2 to 4 inch, max. 1 bar). For hot drinking water the lead-free brass compression fittings 313 and 314. For radiator connections in tight spaces the Minigebo compact adapter with hex drive. GF PRIMOFIT covers the same field with seal colours: NBR yellow, EPDM blue, FKM green up to 150 °C (for heating systems in the black PRIMOFIT finish), FIREJOINT red for gas inside buildings.
| Solution | Pipe | Outside diameter | What it does |
|---|---|---|---|
| Compression fittings for steel pipe Gebo · 150 / 220 · NBR | steel pipe (threaded pipe) | 17.2–114.3 mm | Water, gas outside buildings, compressed air, heating-oil filling lines. Types A/I (male/female thread), O (coupling), T (tee), reducer, end cap. Flange versions from 76.1 mm. |
| Compression fittings for steel pipe Gebo · 151 / 222 · EPDM | steel pipe (threaded pipe) | 17.2–114.3 mm | Drinking-water version of series 150/220: same body, EPDM seal, cold water up to 25 °C. Retrofit seals (EPDM moulded rings) are stocked. |
| Compression fittings for boiler tube Gebo · 15S / 22S | boiler tube (black steel tube) | 20–108 mm | For boiler tubes 20 to 108 mm (heating systems) where welding is not possible for safety reasons. Heating water 80 °C / 6 bar, compressed air. |
| HTB compression fittings for gas inside buildings Gebo · 180 / 225 · HTB | steel pipe (threaded pipe) | 21.3–114.3 mm | Higher-thermal-resistance (HTB) version for gas inside buildings: fire-resistant 30 min up to 650 °C. Series 180 (21.3-60.3 mm) max. 5 bar, series 225 (76.1-114.3 mm) max. 1 bar. Often used between the house entry and the internal installation. |
| Brass compression fittings for hot drinking water Gebo · 313 / 314 · EPDM | steel pipe (threaded pipe) | 21.3–76.1 mm | Lead-free brass for hot and cold drinking water (85 °C / 6 bar hot): repairs in galvanised hot-water lines and transitions to other pipe types. |
| Compact adapters (Minigebo) Gebo · 303 / 304 | steel pipe (threaded pipe) | 17.2–33.7 mm | Compact adapter with clamp connection and male thread, tightened with a hex key: radiator and drinking-water connections on steel pipe in tight spaces. Nickel-plated version for radiators only. |
| Compression fittings for steel pipe GF · PRIMOFIT | steel pipe (threaded pipe), boiler tube with seal set | 17.2–114.3 mm | Pre-assembled, no disassembly, up to 3° deflection per joint – seal colour codes the medium: NBR for gas (outside, 10 bar), water, compressed air – EPDM for drinking water (16 bar, 95 °C warm) – FKM (green) for heating/steam up to 150 °C – for heating systems GF specifies the black-finish PRIMOFIT with FKM. |
| HTB compression fittings for gas inside buildings GF · PRIMOFIT FIREJOINT (HTB) | steel pipe (threaded pipe) | 21.3–60.3 mm | The HTB version of PRIMOFIT: the only PRIMOFIT seal permitted for gas inside buildings in Germany, 5 bar / 60 °C. |
Service limits per medium
The values are manufacturer data from the catalogues; the installation instructions of the series prevail. Two things stand out: drinking water is limited to 25 °C (cold) for malleable iron – warm drinking water is the domain of the brass series; and gas outside and inside are two different things (rule of thumb FR-19).
Show full table · more than 20 rows
| Solution | Medium | max. °C | max. bar | Condition |
|---|---|---|---|---|
| Compression fittings for steel pipe Gebo 150 / 220 · NBR | water (not drinking water) | 25 | 10 | up to 3/4 inch – 16 bar from 1 inch |
| Compression fittings for steel pipe Gebo 150 / 220 · NBR | heating water | 80 | 6 | – |
| Compression fittings for steel pipe Gebo 150 / 220 · NBR | gas outside buildings | – | 5 | from DN 15, ambient -20 to +60 °C |
| Compression fittings for steel pipe Gebo 150 / 220 · NBR | heating oil EL (filling lines) | 40 | 6 | filling lines only, from DN 15, up to 2 inch (TRBF) |
| Compression fittings for steel pipe Gebo 150 / 220 · NBR | fixed water extinguishing systems | – | 12.5 | from DN 25 (VdS) – 16 bar for series 220 |
| Compression fittings for steel pipe Gebo 150 / 220 · NBR | compressed air | – | 12.5 | series 220: 10 bar |
| Compression fittings for steel pipe Gebo 151 / 222 · EPDM | drinking water, cold | 25 | 10 | up to 3/4 inch – 16 bar from 1 inch |
| Compression fittings for boiler tube Gebo 15S / 22S | heating water | 80 | 6 | – |
| Compression fittings for boiler tube Gebo 15S / 22S | compressed air | – | 12.5 | series 22S: 10 bar |
| Compression fittings for boiler tube Gebo 15S / 22S | heating oil EL (filling lines) | 40 | 6 | 57 mm only, filling lines |
| HTB compression fittings for gas inside buildings Gebo 180 / 225 · HTB | gas inside buildings | – | 5 | series 225 (76.1-114.3 mm): 1 bar – ambient -20 to +60 °C – fire-resistant 30 min / 650 °C |
| Brass compression fittings for hot drinking water Gebo 313 / 314 · EPDM | drinking water, cold | 25 | 10 | – |
| Brass compression fittings for hot drinking water Gebo 313 / 314 · EPDM | drinking water, warm | 85 | 6 | – |
| Compact adapters (Minigebo) Gebo 303 / 304 | drinking water, cold | 25 | 10 | brass version only |
| Compact adapters (Minigebo) Gebo 303 / 304 | drinking water, warm | 70 | 6 | brass version only |
| Compact adapters (Minigebo) Gebo 303 / 304 | heating water | 70 | 6 | – |
| Compression fittings for steel pipe GF PRIMOFIT | gas outside buildings | 70 | 10 | NBR – 5 bar with threaded connection – inside buildings only FIREJOINT (Germany) |
| Compression fittings for steel pipe GF PRIMOFIT | water (not drinking water) | 80 | 16 | system water, compressed air, oil: NBR |
| Compression fittings for steel pipe GF PRIMOFIT | drinking water, cold | 25 | 16 | EPDM, galvanised or stainless |
| Compression fittings for steel pipe GF PRIMOFIT | drinking water, warm | 95 | 16 | EPDM |
| Compression fittings for steel pipe GF PRIMOFIT | heating water | 150 | 10 | FKM, black version (also steam, water-glycol) |
| HTB compression fittings for gas inside buildings GF PRIMOFIT FIREJOINT (HTB) | gas inside buildings | 60 | 5 | NBR + graphite |
Manufacturer data; the installation instructions of the respective series apply.
Reading the types
The type designation says what happens at both ends: A clamps on one side and carries a male thread on the other (connection to fitting or valve), I the same with female thread, O clamps on both sides (coupling – also reduced OR and long OL when a pipe section is replaced), T clamps on both sides with a female-thread outlet, WA/WO are elbows, EK the end cap for closing. An appended F (AF, IF, OF, TF) is the flange version from 2 1/2 inch: instead of the cone nut a flange plate with bolts tensions. An appended T (AT, OT, IT) is the HTB version.
Measure the outside diameter, do not guess the nominal size. One inch is 33.7 mm on threaded pipe, 31.8 mm on boiler tube – the same fitting does not fit both. Boiler-tube series have their own article numbers (02.150.…), threaded-pipe series 01.150.… Rule of thumb FR-17.
What we stock
Gebo types A, I, O, T in 1/2 to 2 inch are stocked (tee up to 1 1/2 inch); the 3/8 inch size and the flange versions AF, IF, OF, TF in 2 1/2 to 4 inch are listed and available to order. Also stocked: the EPDM moulded rings for drinking water and Minigebo in brass and nickel-plated; GF PRIMOFIT couplings, transition pieces with male and female thread, tees, elbows and caps 1/2 to 2 inch (EPDM stocked, NBR partly). Stocked sizes are in bold; everything else we procure. Quantities and prices on request.
Show full table · more than 10 rows
| Type | Family | Sizes (stocked in bold) |
|---|---|---|
| PRIMOFIT end cap GF | Compression fittings for steel pipe | 1/2" EPDM, 3/4" EPDM, 1" EPDM, 1 1/4" EPDM, 1 1/2" EPDM, 2" EPDM |
| PRIMOFIT coupling GF | Compression fittings for steel pipe | 1/2" EPDM, 1/2" NBR, 3/4" EPDM, 3/4" NBR, 1" EPDM, 1" NBR, 1 1/4" EPDM, 1 1/4" NBR, 1 1/2" EPDM, 1 1/2" NBR, 2" EPDM, 2" NBR |
| PRIMOFIT tee GF | Compression fittings for steel pipe | 1/2" EPDM, 1/2" NBR, 3/4" EPDM, 3/4" NBR, 1" EPDM, 1" NBR, 1 1/4" EPDM, 1 1/4" NBR, 1 1/2" EPDM, 1 1/2" NBR, 2" EPDM, 2" NBR |
| PRIMOFIT tee, female-thread outlet GF | Compression fittings for steel pipe | 1/2" EPDM, 1/2" NBR, 3/4" EPDM, 3/4" NBR, 1" EPDM, 1" NBR, 1 1/4" EPDM, 1 1/4" NBR, 1 1/2" EPDM, 1 1/2" NBR, 2" EPDM, 2" NBR |
| PRIMOFIT transition, male thread GF | Compression fittings for steel pipe | 1/2" EPDM, 1/2" NBR, 3/4" EPDM, 3/4" NBR, 1" EPDM, 1" NBR, 1 1/4" EPDM, 1 1/4" NBR, 1 1/2" EPDM, 1 1/2" NBR, 2" EPDM, 2" NBR |
| PRIMOFIT transition, female thread GF | Compression fittings for steel pipe | 1/2" EPDM, 1/2" NBR, 3/4" EPDM, 3/4" NBR, 1" EPDM, 1" NBR, 1 1/4" EPDM, 1 1/4" NBR, 1 1/2" EPDM, 1 1/2" NBR, 2" EPDM, 2" NBR |
| PRIMOFIT elbow GF | Compression fittings for steel pipe | 1/2" EPDM, 3/4" EPDM, 1" EPDM, 1 1/4" EPDM, 1 1/4" NBR, 1 1/2" EPDM, 2" EPDM |
| A Gebo | Compression fittings for steel pipe | 3/8", 1/2", 3/4", 1", 1 1/4", 1 1/2", 2" |
| AF Gebo | Compression fittings for steel pipe | 2 1/2", 3", 4" |
| I Gebo | Compression fittings for steel pipe | 1/2", 3/4", 1", 1 1/4", 1 1/2", 2" |
| IF Gebo | Compression fittings for steel pipe | 2 1/2", 3", 4" |
| O Gebo | Compression fittings for steel pipe | 1/2", 3/4", 1", 1 1/4", 1 1/2", 2" |
| OF Gebo | Compression fittings for steel pipe | 2 1/2", 3", 4" |
| T Gebo | Compression fittings for steel pipe | 1/2", 3/4", 1", 1 1/4", 1 1/2", 2" |
| TF Gebo | Compression fittings for steel pipe | 2 1/2", 3", 4" |
| EPDM drinking-water seal (retrofit) Gebo | Compression fittings for steel pipe | 3/8", 1/2", 3/4", 1", 1 1/4", 1 1/2", 2", 2 1/2", 3", 4" |
| Minigebo (Ms = brass, Ni = nickel-plated) Gebo | Compact adapters (Minigebo) | 1/2" Ms, 1/2" Ni, 3/4" Ms, 3/4" Ni, 1" Ms, 1" Ni |
Further in the topic
In the topic: Joining without welding – the entry page · Compression fittings for PE, PP, PVC-C and steel–plastic transition · Repair clamps and tapping clamps · Tool: which solution fits?
From the knowledge base: Pipe dimensions: threaded pipe and boiler tube in the pipe finder · Malleable-iron threaded fittings · Megapress: pressing on steel pipe as an alternative · Gas only with the version approved for it
Frequently asked questions
Can I replace a pipe section with a compression fitting?
Yes: cut the pipe out, insert the new piece, a coupling type O at both ends – the long version OL when the new piece cannot be pushed in.
Which seal for heating water?
NBR (series 150/220) up to 80 °C and 6 bar. For drinking water EPDM, for steam and glycol GF PRIMOFIT with FKM seal (green, up to 150 °C).
Does the fitting take tension too?
Yes, malleable-iron and brass compression fittings are force-fitting, i.e. resistant to tension and shear, and can be deflected up to 3° per side (6° per coupling). They are suitable for equipotential bonding.
Does the pipe need deburring or bevelling?
Cut square and deburred, outer surface clean, undeformed, free of thread, paint and burr in the clamping area; the rest is in the manufacturer’s installation instructions.
Leaking pipe, extending a line, joining two systems?
Send us what you have – pipe type, measured outside diameter, medium, drawing. We tell you which solution fits from stock and what is procured.
Send an inquiryYour inquiry to Zickwolff
Send us what you have – designation, standard, quantity, date. We will clarify the rest with you.
One item or a question
Send inquiry
Not in stock? We procure it – single items too.
Designation, standard and quantity are enough.
Several items
Send bill of materials
200 items? One parts list is enough – we deliver complete.
Attach it as a file.
Helpful if already known: project and country, date needed, certificates, packaging and language of the packing lists. If anything is missing, we will ask.
It is urgent
Request express
When do you need it? Express delivery, to the site if required.
Tell us by when you need the material – we will tell you what is possible.
As of 2026-10-03. Manufacturer data from the Gebo sub-catalogues 2026 (gebooriginal, gebounifix, multigebo, minigebo, polygebo), the Gebo general catalogue 2026/27 and the Gebo product data (gebo.group), the GF PRIMOFIT technical catalogue (2025) and the GF WAGA MULTI/JOINT 3000 Plus technical manual – evidence class H (authorised distributor). Service limits are manufacturer data; the installation instructions of the respective series prevail. Availability per our article master (as of 2026-09-04), without quantities. No installation instructions, no legal advice – gas installations belong in the hands of the licensed installer.