R
11
3.4 CURVED SURFACES
Using a flat dolly on a curved surface can produce misleading results.
The gap between the flat and curved surfaces will not be filled by the adhesive, resulting in one or more of
the following effects:
1. The dolly may peel or twist off instead of being pushed off.
2. The surface area to which pressure is applied, will be modified. This will
lead to results from different curvatures not being comparable.
3. The amount of adhesive may not be sufficient to withstand the exerted
force, resulting in the adhesive breaking before the coating separates from
the substrate.
These difficulties are overcome by using curved dollies on diameters of less
than approximately 2 m (6 ft 7"). An extensive range of curved dollies is
available. See “Curved dollies” on page 18.
Curved and flat dollies are all used in the same way, matching the marks on the
dollies with the longitudinal axis on the pipe.
3.5 CUTTING AROUND THE DOLLY
A dolly cutter is available which cuts through the coating to isolate the coating area under the dolly. It should
be noted that some coatings will be damaged by such an operation, which may cause micro-cracks. Use of
a dolly cutter should be agreed before testing starts.
The dolly cutter is an optional accessory. See “Spares and accessories” on page 17 for ordering details.
Figure 4. Curved dollies
To Next Page
Loading...
Need help?
General
