Full Description

Invention background

This invention relates to wrapping a corrosion protective tape known as cold wrap tape wrapped over buried steel pipes, where the protective tape prevent water in the soil from reaching the pipe's surface causing it to corrode.

To lay the buried pipes underground, a trench is made along the path, then the pipes are laid in this trench, and welded together to form a long pipeline. After completing the laying of the pipes, the trench is then backfilled with soil on the pipe to bury it. Burying pipes underground is normal and does not harm them, as they are made from specially specified steel to ensure that it can pass the fluid inside it and withstand the stresses surrounding its external surface. The predominant material from which the pipes are made is carbon steel, and because this type of material is not corrosion resistant, pipes are covered at factory with corrosion proof protective coatings, except for the pipes ends (joints-welding areas), as welding will result in burning of the protective material due to the excessive welding heat, also, fittings and pipe spools which can't be coated at factory and have to be protected at site, and in order to avoid damage to these areas of the pipes, the protection tape is wrapped on top of them after the welding process is completed at site and before burying the pipes to protect them from corrosion that in turn well lead to pipe leakages of what is inside, especially since pipelines are under high internal pressures.

To avoid this problem, the best technology currently in use is to wrap a tape containing an adhesive substance known as cold wrap tape around the pipe, and this layer is called the insulating layer. This tape sometime is protected by a second protective fabric - called the protective layer - which is made of a non-woven synthetic faux wool fabric. The second protective layer protects the first tape - the cold wrapped tape - from the backfilled soil stresses that surrounds the pipe to bury it, and since the second layer (the protective tape (the fabric)) does not contain adhesives, it is tightened in place with a duct tape (pressure sensitive packaging tape). This third layer is called the fixing tape, this duct tape - the fixing tape - loses its need after burial and soil compaction, so the need for it is temporal, from wrapping to burial, backfilling and compacting only.

The problem lies in the duct tape (the third installed layer), where the pipe may remain exposed for several days or weeks before burial. And during or before backfilling into the trench and with direct exposure to sun light and then the mechanical movement of soil during backfilling, this duct tape which has lost its adhesion will not stick and subsequently falls, especially in hot climate, and as a result the protective fabric layer (Figure (1)) surrounding the insulating tape - the cold wrapped tape - get loosened, making it fails to mentain its function in Protecting the insulating tape, which in turn - the insulating tape - sag and wrinkles forming pockets that allow water to reach the surface of the pipe and cause it to corrode, causing leakage of the pipe content.

Since the use of duct -packaging pressure sensitive- tape to fix the protector (fabric) is impractical and requires immediate burial of the pipe, we have replaced it with Velcro hooks tape, a fabric containing precise hooks that have the ability to mechanically hold the synthetic wool fabric in the second protective layer tight. These Velcro hooks are less affected by environment than duct tape because their way of working is mechanical anchor, with no adhesive needed, and therefore they can retain their ability to grasp the fabric for several weeks. Other technologies are to wrap tape of other polymeric materials such as high-density polyethylene PE, high-density polyethylene HDPE, polypropylene PP, PVC or Elastomeric tapes to isolate pipes, fittings and pipe welding joints. But by leaving the pipe without backfilling for a period, the adhesive fails to maintain its strength and therefore the pipe losses its protection, also, the tamping movement over the pipe may lose the tape ability to stick.

General description of the invention

The invention relates to the protection of buried underground pipes, often made of carbon steel. Because this type of material does not resist corrosion, it is covered at factory with protective coating except at ends (welding joint), where welding will result in burning the protective material due to excessive welding heat. Joints, spools and fittings must be protected by coating, at site after welding and before burying the pipe to protect them from surface water in soil, which in turn corrods those areas, thus ruining the pipe, and leaking what is inside.

The invention is summarized in wrapping three layers on buried piping to protect them from corrosion by water in soil, and the three layers are:

The first layer: the "insulating tape" surrounding the pipe known as cold wrap tape, and it has an adhesive from one side that sticks directly to the surface of the pipe.

The second layer: the protector which follow the first layer and made of non-woven synthetic faux wool fabric.

Third Layer: Velcro hooks tape with fine hooks that can grip and securely hold the second layer -the protector- of faux wool fabric.

The second- and third-layers work as Velcro to secure the second layer (the protector) and protect the first layer (cold wrap tape) from the effect of soil and tamping over the pipe.

The second layer - synthetic wool - protects the first layer - the cold wrapped tape - from the mechanical impact of the soil during backfilling or tamping.

Drawings brief explanation:

Figure 1: A cross section of the pipe showing the mechanical effects on the protective tape surrounding the pipe and the formation of pockets during backfilling, allowing water to leak.

Figure 2: shows a longitudinal section of the pipe and the first insulating layer.

Figure 3: Shows how fabric with fine hooks grips the faux wool fabric.

Figure 4: shows the method of fixing the Velcro hooks tape on the synthetic wool tape.

Detailed description

Figure (1) shows a pipe (1) in a trench (4) and clearly shows the mechanical effect of the soil on the cold wrap tape (2) (or the insulating tape) surrounding the pipe (1) during the process of backfilling and tamping, as the wide arrows (8) are shown in the figure (1) The mechanical direction of soil movement during backfilling and its effect on the cold wrap tape (2) especially from the sides of the pipe (1) from the point of its contact with the trench floor (4) where the cold wrap tape moves (2) due to the movement of the backfill downward forming pockets (3) ) The sagging of the cold wrap tape (2) is caused by the mechanical action of the backfill. To reduce the effect of soil backfilling on the cold wrap tape (2), a non-woven fabric of synthetic faux wool is wrapped (5) called the protector, and the protector (5) is fixed with duct tape pressure sensitive packaging with adhesive from one side adhesive (not shown in the drawings), but weather and Heat from sun and dust lead to weakening the adhesive on the duct tape, thus not tightening the protector (5) and thus weakening the tension of the cold wrap tape (2) on the pipe (1). So, the cold wrap tape (2) is wrapped on the pipes, and it must be protected with a protective layer (5) that protects it from the movement of the surrounding soil, especially during backfilling. It sags and wrinkles forming pockets (3) that allow water to enter to the outer surface of the pipe (1), and with time groundwater leakage, the pipe corrodes, and this leads to pipe ruined (1) and the leakage of what goes through the pipe (1) to the soil.

To avoid the problem of forming pockets (3), the cold wrap tape (2) should be secured to the pipe (1), and as shown in Figure (2), the pipe (1) is protected by cold wrap tape (2), and then a layer of non-woven fabric made from synthetic faux wool is wrapped on top of it (5), where this layer performs two functions, the first is to protect the cold wrap tape layer (2) located below it from mechanical damage that the soil may cause during backfill, and thus maintain the quality of the cold wrap tape ( 2) its integrity which will protect the pipe (1) from damage, as it will also hold the synthetic wool (5) the third layer made of fine fabric hooks (6), where the two layers of synthetic wool (5) and the hooks (6) work as Velcro® (Figures 3 and 4) to secure the cold wrap tape (2 ) and the synthetic wool layer (5), thus reducing the damage to the cold wrap tape (2) during backfilling, as the soil will first hit the synthetic wool layer (the protector)(5), which will absorb the stress of the soil and its movement over it and any mechanical operations above the ground after backfilling, such as compacting the ground, for example. Then the tightness of the protective tape (5) or the cold wrap tape (2) will prevent the formation of wrinkles and pockets (3) from which underground water seeps into a pipe (1).

Figure (3) shows the installation of the synthetic wool layer (5), and the hook layer (6), where the hooks work to connect with the bristles of the synthetic wool layer (the protector) (5) to secure the synthetic wool fabric (5) in place after it is wrapped on the cold tape (protector) (2). As shown in Figure (4), the layer of hooks (6) is fixed on the layer of synthetic wool (5) in the positions of the ends and the beginnings often, and some hooks tapes (6) may be used in other places for fixing as needed.