Squeeze-off of PE pipes and jacketed pipes

When is squeeze-off used?

Squeeze-off is a method for shutting off a live PE pipeline while work is being carried out on it: a squeeze-off tool flattens the pipe between two clamping bars until the flow stops. The method is typically used for repairs, installation of fittings or relocation of branch connections on PE80 and PE100 gas and water pipelines.

Squeeze-off differs from temporary pinching (klemmelukning), which is only used for temporary protection of unpressurised pipe ends. During squeeze-off, the pipeline is under operating pressure, which imposes strict requirements on tools, pipe type, personnel and documentation.

The scope of application is determined by the manufacturer and regulatory standards: for PE80/PE100 gas pipelines, DVGW GW 332 typically covers operating pressures up to 4 bar; for water pipelines, the network owner's rules and current product instructions must be followed. Always check that both the pipe and the tool are approved for the specific task before clamping.

What is temporary pinching used for?

Temporary pinching is the temporary closure of a plastic pipe using a squeeze-off tool: a clamp is tightened around the pipe and flattens it to prevent dirt, debris or water from entering the pipeline during storage and construction. The tools are designed for PE80 and PE100 pipes in SDR 11 and SDR 17, and the pipe must not be under pressure when clamped.

The tool is never a shut-off device: clamping alone does not guarantee a complete seal, and pressure testing must never be carried out against the squeeze-off tool. For pressure testing and permanent pipe closure, a dedicated shut-off solution (e.g. squeeze-off sealing saddles or pressure stoppers) designed for the test pressure must be used. If a pipeline must be closed while under pressure, the method is squeeze-off – not temporary pinching.

The range of tools typically extends from small diameters up to Ø250 mm: manual tools for smaller sizes and hydraulic tools for larger ones. Larger diameters, up to Ø630, can also be squeezed off, but require tools, stops and procedures approved by the manufacturer for that specific diameter and SDR class (product-specific). The diameters covered by your tool and the SDR class it is designed for are stated in the tool manufacturer's instructions.

Requirements for stops, distances and clamping

The squeeze-off tool features built-in stops that limit how far the pipe may be flattened. The pipe must not be squeezed further than permitted by the tool's stops, and the same spot on the pipe may only be clamped once. If clamped in the same spot again, or if squeezed beyond the stop, the pipe wall thickness is permanently damaged.

The distance to welds, fittings and previous clamping points is critical: most instructions specify at least four times the outer diameter of the pipe from these locations, as the squeezed area is weakened and can no longer support a weld or a fitting.

Clamping time must also be limited: after clamping, a maximum clamping time of approximately six hours is normally recommended, after which the pipe must be released again. Longer clamping times can cause permanent deformations and stresses in the material.

After completion of clamping, the pipe is depressurised in a controlled manner, and ovality is restored using a re-rounding tool. Previously squeezed pipes must be marked with special tape ("Squeeze off applied") if an electrofusion coupler is not welded over the clamping locations afterwards – preventing anyone from clamping or welding in the same spot again. Read more in the articles on re-rounding tools and squeeze-off. If the pipe needs to be closed from the inside without being deformed, a pipe plug or balloon stopper is the alternative.

Setting stop blocks according to SDR

The stop blocks are what make squeeze-off controllable: they limit how far the clamping bars can flatten the pipe so that the deformation matches the exact wall thickness of the pipe – i.e. its SDR class. An SDR 11 pipe with a thick wall and an SDR 17 pipe with a thin wall must not be squeezed to the same depth, and the tool must be approved for both classes if used for both.

Set the stop blocks according to the wall thickness stated on the pipe (measure if necessary), in accordance with the tool manufacturer's chart and DVGW GW 332. Never squeeze beyond the setting, and check before use that the stop blocks are rigid and not worn or adjusted by others.

The clamping zone must be clean and free of dents, and the clamp must be positioned on a straight section of pipe with adequate distance to welds, fittings and previous clamping points. Manufacturers typically specify at least a multiple of the pipe diameter to these locations; exact values follow the tool and pipe manufacturer's instructions.

Distance from squeeze-off tool to pipe end

The clamping point must be located far enough from fittings, joints and pipe ends to ensure the pipe wall deforms evenly without skewing. Regulations specify a fixed rule: the clamping point must be located more than 5 times the outside diameter of the pipe from the nearest fitting, joint or other clamping point. This rule also applies when the same section is to be squeezed off twice in succession.

The distance is measured from the edge of the fitting or joint to the nearest edge of the squeezed area – not to the centre of the tool. For Ø110 this means more than 550 mm, and for Ø250 more than 1,250 mm. If there is insufficient space along the section, an alternative solution must be chosen, such as plugging instead of clamping.

Clamping is also limited by wall thickness. The typical limit for standard squeeze-off is diameters below 160 mm and wall thicknesses below 10 mm; larger pipes and thicker walls require tools, stops and procedures approved by the manufacturer for that specific combination. Therefore, larger dimensions are listed as product-specific in the table: there is no single universal value applicable to all tools.

Stops, shafts and clamping components

The tool's stops are a safety and functional component: they define the maximum clamping depth and must never be removed, adjusted or bypassed. Shafts, spindles and clamping bolts in the squeeze-off tool are likewise determined by the manufacturer. There is no generic standard for recommended shaft diameter across different brands; values must be taken from the specific tool's instruction manual.

Inspect the tool before use: stops must be rigid, threads and spindles must be intact and smooth-operating, and clamping surfaces must be clean and free of sharp edges that could cut the pipe. Damaged clamping components mean the tool must be taken out of service.

Jacketed pipes: remove the outer jacket (peelable layer) before squeeze-off

Jacketed pipes – e.g. PE100-RC with a sprayed or co-extruded protective layer – must never be clamped with the outer jacket intact. The protective layer has a different thickness and material property than the core pipe, and if clamped together, the layers deform unevenly: the clamp cannot achieve a tight seal, deformation becomes unpredictable, and the core pipe may be damaged.

Therefore, the peelable jacket must be removed across the entire clamping zone prior to squeeze-off – leaving a generous margin beyond the width of the clamping bars on both sides so that the tool grips only the core pipe itself. Use a suitable jacket stripping/peeling tool, and leave a clean, smooth transition so the clamping bars do not cut into the edge of the jacket.

This rule is firmly established in regulations: DVGW GW 332 (and associated tool instructions) requires that the applied jacket (peelable layer) is removed in the clamping zone before the pipe is squeezed off. The core pipe itself is subsequently treated as a standard PE pipe: the surface in the clamping zone is inspected afterwards as described in the post-treatment section.

Re-rounding and post-treatment

Once work is complete, the clamp is released in a controlled manner (depressurisation) and the pipe is re-rounded: ovality is corrected using a suitable re-rounding tool (re-rounding clamp) until the pipe is round again – see the article on re-rounding tools. An oval pipe provides poor conditions for any subsequent welding or fitting installation.

After re-rounding, inspect the clamping zone: the surface must be intact, free of cracks, flaking, burn marks or permanent grooves. Clamping locations must be marked with special tape ("Squeeze off applied") if an electrofusion coupler is not welded over the area afterwards – preventing anyone from clamping the same spot again; a squeezed-off location is only intended for a single squeeze-off operation.

Welding or installing fittings directly on the clamping zone is prohibited: the area is deformed and unsuitable for joining. Furthermore, observe the manufacturer's minimum distance from the clamping location to the nearest weld or fitting.

Standards and regulations: DVS and DVGW GW 332

DVGW GW 332: the German code of practice on squeeze-off (Abquetschen) of PE80 and PE100 gas pipelines – the primary reference for requirements regarding tools, stop blocks, jacket removal, clamping zones, repeated clamping and post-inspection. In practice, it is also used outside Germany as a professional reference framework.

DVS regulations (e.g. DVS 2207-1 for butt welding and associated technical bulletins) address the implications for subsequent welding: no welding on clamping zones, scraping of oxidation layers and checking of ovality prior to welding.

DS/EN 12132: European standard on squeeze-off of PE pipes (principles, clamping bar geometry and tool testing requirements).

Pipe and tool manufacturer instructions: specific stop dimensions, SDR intervals, clamping times and distances must always be followed for the specific combination of pipe and tool. Only trained personnel using approved tools may perform squeeze-off work, and the work must be documented in accordance with standard pipeline closure procedures.

Regulations for pipe closure and pressure testing

DS/EN 805: requirements for water supply systems, including pressure testing methods, holding times and evaluation. The standard has been revised (latest edition 2026) and now explicitly mentions viscoelastic pipes such as PE; closures and thrust blocks at pipe ends must be dimensioned for the test pressure, which is precisely why squeeze-off tools must never be used as pressure test stoppers.

DVGW W 400-2: German regulatory framework detailing pressure testing procedures for PE pipelines (including the contraction method); frequently used as a practical reference, including in Denmark.

DS/INF 70-6: Danish informative guidance document on practical plastic welding; used as a professional reference framework, not as a standard.

Pipe and tool manufacturer instructions: specific dimensions for stops, distances, SDR approvals and clamping times are found here, as temporary pinching is not covered by a cross-manufacturer product standard.