The invention relates to a clamp for mounting a substantially cylindrical elongate member according to the preamble of claim 1.

Background of the invention

Tubes or pipes for the transportation of gas, oil or other liquids are usually fastened to a base with clamps, which consist of two clamp halves which are designed to encompass the pipe or tube. Depending on the tube diameter, the operating pressure of the system and strains acting on the tube and its mounting, different kind of clamps are available on the market.

Tubes for gas or oil are usually fabricated of metal, most commonly of stainless steel. Transport pipelines are often subjected to very demanding environmental conditions with increased risk of corrosion. Environments with increased occurrence of corrosion of materials include offshore vessels and platforms, as well as coastal facilities, due the presence of highly conducting sea water with high chloride content as well as oxygen in the marine atmosphere. Special clamps have been designed for mounting pipes or tubes in such conditions.

Generally the stainless steel material of the tubes is protected from corrosion by a protective layer. Stainless steel will however start to corrode once the protective layer is damaged and/or its formation is hindered.

In crevices and confined spaces on top of or between metal parts, where water and/or dirt can accumulate, the passive layer of the stainless steel is weakened and once the layer is damaged it cannot recuperate. This so called crevice corrosion has been a serious problem in pipe installations offshore and in coastal areas. Leaking of a pipeline damaged by corrosion can cause hazards such as environmental hazards, fire or explosions. It is therefore important to develop measures to prevent crevice corrosion.

When designing new clamp types it is important to choose a suitable material and shape in order to minimize corrosion of the pipeline. Different clamp types have been developed for this purpose.

From WO12003905 Al a clamping device is known having an inner surface for receiving the outer wall of a pipe or tube, which is provided with a sacrificial material that will be consumed in the case of onset of corrosion. In the corrosion process, the materials of the pipe and the clamp act as a galvanic couple. The purpose of the sacrificial material is to act as an anode that will be consumed by corrosion, thus saving the tube from corrosion. A non-iron metal is used as sacrificial material and it is added to the inside of the clamp as a smooth surface. However, small irregularities will usually be present on the inner surface of the clamp as well as on the surface of the tube. Water and dirt can accumulate in these small crevices between clamp and pipe surfaces, causing corrosion. It will be necessary to replace the clamp relatively often, which can be bothersome as pipelines are often located in remote areas.

Clamp types have been designed with the aim to reduce water accumulation and thus corrosion between the clamp and the tube. A plastic material clamp is known from the prior art which inner clamping surface is provided with elastomer strips in order to maintain drainage channels between the tube and the clamp and thus to prevent the accumulation of water. However the production of this clamp type is laborious, as the elastomer strips need to be added to the inner surface of the clamp in a separate work phase. Also crevices are often present in the contact area between the elastomer strip and the tube, for example on the sides of the strip area. Water left in these crevices will again cause the tube material to corrode.

Objective of the invention

It is objective of the invention to provide a clamp for tubes or pipes that eliminates the drawbacks of clamps of the prior art as outlined above. Furthermore it is objective of the invention to provide a tube or pipe clamp that is suitable for the use in demanding environments with increased risk of corrosion and that is suitable for mass production. Brief description of the invention

The problems outlined above are solved by a clamp according to the characterizing portion of claim 1.

The invention relates to a clamp for mounting a substantially cylindrical elongate member, such as a tube or pipe. According to the invention the clamp comprises an upper and a lower clamping member, each having a receiving portion to engage approximately half of the peripheral surface of a part of the elongate member. According to the invention each clamp member has through holes for mounting means arranged on each side of the receiving portion. The through holes of the two clamping members are aligned in a way that the clamping members can be pressed against each other by the mounting means in order to encompass the peripheral surface of the elongate part arranged between them. Additionally the receiving portion of each clamp has a substantially semicircular cross-sectional profile and is provided with ribs substantially parallel to the longitudinal direction of the elongate member, which are protruding radially inward, and each rib has a partly circular cross-section. According to one embodiment of the invention each rib of the receiving portion has a semi-circular cross-section and the ribs are arranged at regular intervals along the circumference of the receiving portion.

According to another embodiment of the invention each clamp member is a cast part or a segment of a bar profile fabricated by extrusion.

Alternatively the ribs form an integral part of the clamp member. The clamp can thus be produced in one piece. It is an option that the clamp is fabricated of a metal alloy less noble than stainless steel, which in case of onset of crevice corrosion will act as a sacrificial anode.

It is an option that the clamp is fabricated of aluminum alloy. According to another embodiment the upper and lower clamp member are identically shaped.

A clamp according to the invention offers significant advantages as compared to the prior art.

Due to the shape of the ribs, only line contacts take place between the clamp and the mounted elongated member. The contact area between the parts is minimized, leaving little possibility for water and dirt to accumulate in crevices. The structure of the clamp with many openings and little contact between the clamp and the elongated member means water can drain easily and the clamp can dry easily after periods of exposure to water. This is important, as the entering of water into the mounting cannot always be prevented. As the tube is kept securely in place by several attachment points, that means by several ribs, of the clamp, fastening force is distributed evenly around the tube, which prevents damaging of the tube when the clamp is fastened.

An additional advantage of a clamp according to the invention is that it is well suitable for mass production and can thus be produced in an easy and inexpensive way. A clamp member according to the invention can be fabricated for example by extrusion or by casting. When a clamp according to the invention is made of a metal alloy, for example aluminum alloy, it is also considerable more fireproof than plastic material clamps of the prior art.

List of figures

Figure 1 depicts a clamp member of a clamp embodiment according to the

invention;

Figure 2 depicts a clamp embodiment according to the invention in a clamp assembly with mounting means and a mounted tube in place. Detailed description of the invention

In figure 1 is depicted one clamp member of clamp according to the invention. The clamp member has a receiving portion 3, which has a substantially circular cross- section. Through holes (4, 6 and 5, 7) for mounting means are arranged on each side of the receiving portion 3. The outside of a clamp according to the invention is preferably block shaped, in order to facilitate mounting of the clamp. The upper surface parts 10, 11 are preferably aligned and smooth surfaces in order to facilitate mounting of two clamp members opposite of each other. The clamp member is equipped along the circumference of the receiving portion 3 with regularly spaced ribs 8 protruding radially inward. The depicted ribs 8 have rounded cross-sections. Rounded cross-section of the ribs has the advantage that the contact area between clamp and tube and thus the space for water to accumulate is minimized and also damage of the tube surface is prevented, as the ribs do not have sharp edges. In the depicted clamp the ribs have different widths. It is one option that every other rib has a smaller width. Preferably all ribs have similar widths. Furthermore preferably the ribs have partly circular cross-sections.

Preferably a clamp member according to the invention is symmetrical and preferably both clamp members in a clamp are identically shaped.

The depicted clamp member is well suitable for fabrication by extrusion, as it has a substantially hollow body 9. For the fabrication of a clamp member, first a bar profile with the desired clamp member shape can be extruded. After this segments of suitable width for the clamp member can be cut off. Thus each clamp member can be fabricated in one piece, by extrusion and subsequent cutting. No additional work phases are necessary. For example with a process as depicted, a clamp according to the invention can be fabricated in a simple process well suitable for mass production and automated production. It is also a possibility to cast a clamp according to the invention from one mold.

In figure 2 is depicted an assembly of a clamp according to the invention with a pipe 101 mounted in place. The clamp comprises an upper clamp member 1 and a lower clamp member 2, which are mounted opposite of each other with their receiving portions directed inwards to form a substantially circular space, in which the pipe 101 is received. Ribs 8 distributed evenly along the circumference of the receiving portions 3 abut the outer surface of the pipe 101 and hold it in place. It can be seen that draining channels are present between the ribs 8 and the clamps are designed as hollow parts in order to allow drainage of water. The depicted clamp member and the encompassed pipe are mounted to a base 13 by mounting means 102, in this case bolts.

Even though a clamp according to the invention is especially advantageous when it is used for mounting metal pipes, it can also be used for fixing tubes of different material, for example plastic material or rubber.