Viega Megapress: press connectors for thick-walled steel pipe – ⅜ to 4 inch

What Megapress is meant for – and what it is not

Viega describes Megapress as a replacement for welded, threaded and grooved joints in industrial, heating and cooling installations, in new installations as well as in repairs and extensions of existing plant. The typical use: closed heating and cooling circuits, industrial plant, compressed-air networks, installations for technical gases (after consultation with the manufacturer) as well as fire-fighting water and sprinkler systems. The system is designed for the nominal pressure PN 16.

Two limits are printed on every connector: Megapress is not approved for drinking water – the press connectors carry a black rectangle “Not suitable for drinking water” for that –, and fuel gases do not belong in the standard system. For natural gas, LPG, heating oil and diesel there is the gas variant Megapress G with HNBR sealing element and its own DVGW approval. Whoever installs drinking water reaches for the system-pipe systems with copper or stainless-steel pipe (Viega Profipress, Sanpress, Sanha NiroSan) – the system finder shows per medium and size which system is approved and available from us.

How the joint works: cutting ring, separating ring, sealing element

A Megapress press connector is made of unalloyed steel (material 1.0308) with an electroplated zinc-nickel coating of 3–5 µm that protects it against external corrosion – for instance against condensation on cooling lines. In the bead of the connector sit three parts:

• Cutting ring: during pressing it cuts into the pipe surface and makes the force-locking connection – it holds the pipe against internal pressure and pull-out.
• Separating ring: it lies between cutting ring and sealing element and protects the sealing element from the cutting ring when the connector is pushed on and pressed.
• Profile sealing element: an EPDM element with moulded sealing lips that reliably seals even slightly uneven pipe surfaces – as are usual with black or galvanised steel pipe.

This construction distinguishes Megapress from the press connectors for copper and stainless-steel system pipe: there an O-ring seals on a precisely calibrated pipe, here the connector has to grip reliably a pipe with the tolerances of threaded and boiler tube and with a zinc or paint layer. That is why Megapress has its own limits for the maximum outside diameter per size (see pipe table).

SC-Contur: unpressed means leaking

Like all Viega press connectors, Megapress carries the SC-Contur, a safety feature certified by the DVGW: a joint that has accidentally not been pressed is necessarily leaking at the leak test and shows up before the plant goes into operation. Viega guarantees detectability at the wet test in the range 0.1–0.65 MPa (1.0–6.5 bar) and at the dry test with air or inert gas from 22 hPa to 0.3 MPa (22 mbar–3.0 bar). This allows a plant to be tested dry before filling – in industrial construction a tangible advantage over the weld seam, which can only be judged by visual and pressure testing or non-destructive testing.

Marking on the connector: a black dot stands for EPDM sealing element with SC-Contur, a white dot (Megapress S) for FKM, a yellow dot (Megapress G) for HNBR.

Which steel pipes Megapress joins

Megapress press connectors are approved for seamless (S) and longitudinally welded (W) steel pipes, namely black, galvanised, industrially painted or powder-coated. The pipes must comply with the codes the instructions for use refer to:

• Threaded pipe to EN 10255 – heavy series H, medium series M and the pipe types L, L1 and L2 (Megapress G: only H and M).
• Boiler tube to EN 10220 with EN 10216-1 (seamless) or EN 10217-1 (welded) – pipe series 1, 2 and 3; Viega recommends pipe series 1, because series 2 and 3 are hardly available on the market (Megapress G: only pipe series 1).

That is exactly the pipe we carry as steel pipe in stock: the dimensions to EN 10220 are in our dimension tables for welded steel pipe EN 10217-1 and seamless steel pipe EN 10216-2, the threaded-pipe series H and M in the pipe overview. Whoever picks the size there will see in a row of its own which press and coupling systems are approved for it.

For every size a permissible wall-thickness range applies – limited downwards by the holding force of the cutting ring, upwards by the insertion range of the connector. With coated pipes the maximum outside diameter including the coating must not be exceeded. The following table summarises the Viega pipe overview:

The values are manufacturer statements from the Viega pipe overview; the XL sizes 2½–4 inch exist as Megapress S XL with FKM sealing element. For existing pipes whose standard and series are not known, measuring outside diameter and wall thickness decides – both must lie within the range of the table. Pipes in the sizes 38.0, 44.5 and 57.0 mm are also in the programme as intermediate sizes.

Megapress, Megapress S, Megapress G and XL – the family at a glance

All variants share pipe, connector material, profile and tooling; they differ in the sealing element and thus in medium and temperature:

For Megapress G narrower pipe requirements apply: only threaded pipe EN 10255 of series H and M and boiler tube of pipe series 1. The details on S and XL – FKM sealing ring, Press Booster, flange adapters up to PN 40 – are on the page Megapress S and S XL.

Which medium with which sealing element

Whether a medium may be carried with Megapress is decided by the sealing element, not the connector. EPDM covers water, oil-free compressed air and technical gases; FKM takes over as soon as oil, solar fluid or temperatures above 105 °C come into play; HNBR is reserved for fuel gases and heating oil. The assignment according to the Viega media list (edition 11/2025):

“With restrictions” means: only with the sealing element named in the media list or after consultation with Viega. For media not listed here – process water with additives, refrigerants, chemicals – the manufacturer's approval is to be obtained for the individual case; Viega keeps the complete list as “Fields of application of metallic installation systems”. This overview does not replace the manufacturer approval.

Connection to flange and thread

In pipeline construction a line rarely ends at the press connector: valves, pumps, apparatus and existing lines are flanged or have threads. Megapress brings both:

• Flange adapter (fixed flange): steel 1.0308 with zinc-nickel coating, on one side a Megapress press end, on the other a flange to EN 1092-1 – model 4259 in PN 10/16 and model 4259.1 in PN 6, each in 1¼, 1½ and 2 inch (DN 32, 40, 50). In XL the adapter 2½–4 inch is additionally available in PN 25/40. Dimensions, bolt circles and bolts of the mating flange are provided by the flange dimensional drawing PN 6–40; Viega gives tightening torques per nominal size in the instructions for use (bolts 8.8, hardened washers). Sequence per instructions for use: first make the flange joint, then press.
• Threaded adapters: adapters with female and male thread to EN 10226-1 connect Megapress with threaded fittings, valves and threaded-pipe sections in existing plant.
• To the system pipe: Megapress and the system-pipe systems (Profipress, Sanpress) can only be coupled via threaded or flange adapters, never by mixing the connectors – the profiles and press jaws are not compatible.

Fire-fighting water and sprinkler systems

Megapress is approved for VdS-compliant sprinkler systems – with clear conditions: black, galvanised or powder-coated steel pipes per the requirements of the VdS approval, nominal sizes D ¾ to 2, pipe wall thickness at least 2.6 mm and at most 3.3 mm, use in the pipe network downstream of the alarm valve station (wet and dry systems), permissible pressure 1.6 MPa. Covered are the fire hazard classes LH, OH 1–4, HHP 1–4 and HHS 1–4. Fire-fighting water additives are generally not permitted (exception only after release by the manufacturer and agreement with VdS). Support spacings follow the VdS guidelines, not the heating installation.

What Megapress is not: Prestabo, Profipress, Sanpress – and the Sanha counterpart

Three mix-ups cost time in practice, because pipe and connector then do not fit together:

• Megapress is not Prestabo. Viega Prestabo is a system-pipe system: thin-walled, galvanised precision steel pipe to EN 10305-3 in 12–108 mm with red-marked connectors. It has its own press jaws and press rings; the instructions for use expressly prohibit pressing Megapress connectors with jaws of Profipress, Sanpress, Sanpress Inox or Prestabo. We do not carry Prestabo.
• Megapress is not Profipress or Sanpress. Both join calibrated copper or stainless-steel system pipe in millimetre sizes up to 108 mm and are approved for drinking water; Megapress joins inch-size steel pipe and is not.
• The Sanha counterpart is called SANHA Heavy Steel Press (series 70000): carbon-steel connectors, likewise zinc-nickel coated, for thick-walled steel pipe ½–2 inch to EN 10255 and EN 10220, EPDM up to 120 °C and 16 bar, with gas variant (series 71000, HNBR). We source it on request; in the system finder it stands beside Megapress.

Installation in brief – what differs from the system pipe

1. Cut the pipe square, deburr carefully inside and outside – burrs and sharp edges damage sealing element and separating ring.
2. Check the pipe end for scores, rust and paint runs; coated pipes must not exceed the maximum outside diameter of the pipe table. Remove protective caps from pipe ends only immediately before installation.
3. Mark the insertion depth, push the connector on up to the stop, check the mark.
4. Press with Megapress press jaw (⅜–1 inch) or press ring with articulated tension jaw (⅜–2 inch); XL with press ring and Pressgun Press Booster. Use only the press tools and jaws approved by the manufacturer.
5. Keep minimum distances: to weld seams and bends 3 × D; plan the space requirement of the press rings per instructions for use.
6. Protect pipes against corrosion and insulate them to the recognised rules of technology – the zinc-nickel layer protects only the connector.
7. Leak test wet or dry; unpressed joints show up through the SC-Contur.

Pressing instead of welding

The reason Megapress is used in industrial construction and maintenance is less the joint itself than what is dropped: welding permit, fire watch, gas-free certification, draining and drying the line, welder qualification and weld testing. Viega states, as a manufacturer claim, up to 60 % less assembly time compared with welding, in the XL sizes up to 80 %. What that means for a specific project – and where welding, flange or grooved coupling remain the better choice – is on the comparison page Megapress or welding; the cost comparison calculator works through assembly time, ancillary costs and downtime with your own inputs.

Availability at Zickwolff

The standard names dimensions. What is listed here, we carry – from stock or to order; how quickly a size is available we clarify on request. Megapress we source as a Viega contract dealer directly from the manufacturer: connectors, elbows, tees, reducers, flange and threaded adapters in ⅜–2 inch and XL 2½–4 inch. The matching steel pipe to EN 10255 and EN 10220 is in our stock – pipe and connector come from one source.