Line blinding is a well established maintenance and safety procedure to avoid cross-contamination and pollution during maintenance. While safety and contamination issues are comparatively easy to handle onshore, the tough conditions which offshore applications bring with them are a big challenge for any line blinding concept. Offshore applications – such as on oil rigs and FPSO vessels – pose special problems for valves in general and line blinds in particular. These include issues like flammable and hazardous media, a corrosive sea air atmosphere, high pressure applications, offshore safety procedures and often stormy and changeable weather conditions. Offshore industries have long been looking for a convenient solution to blind lines in a fast and safe way. The traditional way – the installation of conventional spectacle plates – is still an extremely time consuming way to blind lines which comes along with high expenditures in terms of personnel and equipment.
The most convenient solution so far is the installation of line blinding systems which are permanently flanged or welded into the line and which negate the need for the spreading of lines. Fetterolf Corporation introduced the first bolt free line blinding system, the Cam-Set®, years ago. Easily opened by turning a hex nut, the heart of the system – the cam mechanism – gives free the built in spectacle plate immediately. The plate can be swung safely into closed or open position in under a minute - no matter what size of pipeline. The change requires only one person and no tools and is therefore an extremely fast and convenient way to fulfill the required safety procedures.
The latest SchuF Fetterolf development is the sliding line blinding system, the Cam-Slide. Its 4 bolt design requires less space due to its reduced body size and thus has a lower weight and smaller bolting sizes. The Cam-Slide design also allows for much higher pressure applications. The sliding action of the square spectacle plate eliminates the space required by a swinging type line blind. Functional improvements have also been achieved by introducing a bearing block and limit stop to allow accurate and repeatable positioning of the spectacle plate with a definite stopping point. With less effort being required to switch position, it results in less wear of the sealing parts and in return reduces maintenance and servicing needs in the future.