Weather and environmental conditions: rain, moisture, wind and cold in plastics welding

Weather is part of the procedure

The DVS 2207 series covers more than just temperature, pressure and times. The regulations also stipulate that jointing must be carried out under controlled conditions: the components, the machine and the welding zone itself must be protected against rain, snow, driving rain, drafts and direct sunlight, and actual conditions must be documented. If work is carried out outdoors, providing shelter and a dry environment is therefore part of the task — not something to be sorted out afterwards.

This applies to all methods: butt fusion according to DVS 2207-1 (PE), DVS 2207-11 (PP) and DVS 2207-12 (PVC-U), hot gas welding according to DVS 2207-3 and extrusion welding according to DVS 2207-4. The regulations refer to the same basic conditions, while the specific limits for ambient temperature and wind follow the current edition of the standard and the manufacturer's instructions for the machine and pipe.

The practical consequence is simple: if conditions cannot be brought under control, work must be postponed or moved indoors. A joint made in the rain or a draft may look fine on the outside yet contain pores, cold fusion or misalignment.

Rain and driving rain

Water in the welding zone is the quickest route to a poor joint. In butt fusion, water evaporates when the heating element and heated pipe ends meet, trapping steam within the melt line. The result is pores, dark spots and a joint that cannot be documented. In electrofusion welding, the risk is even greater, as water in the annular gap between the pipe and fitting causes an incorrect fusion sequence and, at worst, a cold weld that the control unit fails to detect.

Therefore, do not work in rain or snow, and stop work when the weather changes. After rain, pipe ends, fittings and tools must be thoroughly dried before work continues, and any water inside jacket pipes, couplers or on the underside of the pipe must be drained out — not just wiped off the top. In extrusion welding, the groove must be dry before the welding filler wire is laid in.

Moisture and condensation

Condensation is the hidden adversary. Cold pipes brought into a heated tent or left in the sun will form surface condensation within minutes — even if it is not raining. The same problem occurs when warm components are taken out into cold air, and when tools and heating elements are moved between cold and warm environments.

Store pipes and fittings dry and under cover, keep them raised off the ground, and seal the ends to prevent water or dirt ingress. Allow cold components to acclimatise in the tent before welding, and wipe away condensation with a clean, dry cloth immediately prior to heating. The heating element coating must be kept dry and free of plastic residues — moisture on the element impairs heat transfer and risks damaging the coating.

Wind and drafts

Wind steals heat precisely from the surfaces that need to be maintained at temperature. A heating element exposed to drafts cools unevenly, and the pipe ends cool down while the element is being moved into position. Consequently, the times in the table no longer match reality, and the joint becomes cold even though the machine has run the planned cycle.

Set up shelters so the welding zone is shielded from the prevailing wind direction, and do not face an open pipe end directly into the wind. Wind also carries dust, sand and spray, which settle in the melt and in the groove during extrusion welding. A light tent or windbreak is cheaper than redoing a joint.

If the tent is to withstand wind and frost, erecting it is not enough: anchorage, snow loads and temperature control must be planned before work starts. This is described in mobile worksite in the field.

Cold and frost

In cold weather, PE becomes stiffer and more brittle, making it less resistant to impacts and shocks. This makes components harder to round and align, placing greater demands on clamps and alignment tools to prevent components from being forced into position with stresses locked into the joint. Cold pipes must be handled and lifted carefully and must not be dropped onto frozen ground.

The machine needs time to warm up: hydraulic oil becomes thicker, hoses stiffen, and batteries for logging and displays lose capacity. Run the machine through a dry cycle a couple of times before using it for a documented joint. At the same time, ensure that no snow or ice enters the clamps, welding zone or heating element, and that the ground is stable and non-slip.

Cold also alters cooling. A joint cooling in a cold wind must not be relieved of pressure early just because the surface feels cold — cooling must follow the selected time from the welding tables. If conditions are outside those permitted by the procedure, work must be moved indoors or postponed.

Heat and direct sunlight

Sunlight is not just pleasant. A pipe lying half in the sun becomes warm on one side and cold on the other, resulting in ovality and an uneven melt front. With large diameters, the temperature inside the pipe can exceed the ambient air temperature, invalidating the selected times. Shield components and the machine against direct sunlight using a tent or canopy, and never store pipes intended for welding out in the sun.

If the air temperature exceeds the limits permitted by the procedure and the manufacturer, work must be postponed or moved to a cooler time of day — not compensated for by arbitrarily shortening times.

Setting up the workspace

Choose a tent or shelter solution that provides both protection from wind and a dry environment: a tent with a groundsheet or a sturdy windbreak facing the wind direction so components and equipment remain dry. Ensure that water cannot run across the floor and that the ground is level and load-bearing so the machine does not sink or shift.

Ventilation is part of the protection measures. When welding PVC-U, hydrochloric acid is released, so the work requires extraction and air exchange, and a generator must never be run inside a closed tent due to the risk of carbon monoxide. Power supply and cabling must also be protected against water — see power at the worksite.

Remember lighting: in winter and inside a tent, it becomes difficult to inspect the bead, melt front and cleanliness. Task lighting is part of quality assurance, not a luxury.

Record conditions in the log

Note the air temperature, weather and any wind, as well as the protective measures in use. The fields for weather and ambient temperature are already included in the protocol sections of the welding tables, and this information forms part of the welding log. In the event of a dispute, documentation is what determines whether the joint was made under the conditions required by the procedure.

If work was suspended due to weather, record that too. A suspended operation that is correctly resumed is documentable — an operation carried out straight through in the rain is not.