| Tweet |
Custom Search
|
|
|
||
 TM 55-1905-223-SDC
300 lb./in.2 and the temperature does not exceed 200F. The patch has excellent adhesive qualities when
applied to ferrous and cuprous metals and can be employed for emergency repairs to a variety of damaged
structures having smooth or jagged protruding edges. Plastic patches can be applied under conditions which
delay repairs by other methods and in many cases require permanent repairs or replacements before service
can be restored to the damaged system.
The preparation and application of the plastic patch can be accomplished with basic knowledge and
training. The application of the pipe or surface patch is comparable to that of a battle dressing in first aid, and
the use of the paste is as simple as applying putty.
Plastic patches, when properly applied, are completely effective. In those infrequent instances when
defects occur, the leakage may be found at the extremities of the patch, between the patch and the metal
surface. Such leaks generally are less than one percent and do not become greater. Defects, when they
occur, generally are attributed to faulty preparation or application.
It can be assumed that the speed of application of a plastic patch is basically determined by the size and
type of rupture and the local working conditions. A simple type patch can be applied to a 4-inch pipe in less
than 10 minutes. Various types of damage may require varying preparation times, but once the patch is
properly in place, the type and size of the rupture or the size and shape of the structure have little effect on
the time involved.
The maximum patch life has not been determined, but all indications are that a properly applied patch will
last until such time as a permanent repair or replacement can be made. However, it must be understood that
the patch is an emergency expedient and is not intended, or should it be considered, a substitute for a
permanent repair. The patch is relatively inert, being adversely affected only by excessive (200F.) heat and
concentrated acids.
The success of a properly applied patch is dependent upon two factors, strength and adhesion, and with
these two factors present, the patch will be completely effective. In the process of curing, the patch will have
the tendency to adhere well to metal and other surfaces. The process of applying the plastic patch actually
reinforces the activated resin with fibrous glass material. The reinforcement of the resin greatly increases the
strength when the patch is cured.
Should fibrous glass materials not be available, reinforcing can be accomplished by the use of cloth such
as a blanket or some other material which will absorb the resin. In most cases, reinforcing with such material
will not provide the equivalent strength obtained through the use of fibrous glass materials. Although
substitute materials are highly effective, they are to be used only when materials herein specified are
unavailable.
8-15. TYPES OF PATCHES. Several types of patches are possible for repairing pipes and bulkheads in
diverse locations and with diverse uses. They are described in the following paragraphs:
8-19
|
||
|
||
