Definition of Scraper Trap (throwers and catchers)

The traps scraper constitute tubular systems, part of the inlet or outlet pipeline of a crude oil or gas facility whose function is to allow the access of a cleaning tool to the area of ​​the duct, that is, outside the facility. This cleaning task is carried out to inspect and maintain the oil and gas transportation pipelines. A trap can be a launcher if it is located at the end of the plant installation, when the fluid is directed towards the duct, or receiving well, if conversely it is located in the pipe that receives the fluid coming from the pipeline that will be treated in the plant. Also, there are intermediate solutions, resulting in a combination of the other two.

The trap is attached over the duct line that wishes to be subjected to cleaning. Classically, it has a flat lid with a davit or an opening system to enter or remove the scraper, and on the other end is the reduction that couples with the pipe. This is because, by design, the trap should be at least the nominal diameter immediately greater than the diameter of the duct. On the other hand, the length will depend on the tool to be introduced, if they are the simple

scrapers cleaning or if, in addition, the state gas entity requires a certain length to introduce the so-called "smart scrapers” which are more extensive. In addition, cleaning or drive spheres could be introduced.

Design and Standards

Design standards depend specifically on the installation. In many cases, piping design standards such as those proposed by the ASME entity are used, although in other cases, it may be required to be considered as equipment under pressure, in which case, it will be governed by the standard applicable to containers such as ASME VIII, considering that it will not be exposed to fire straight. Other standards used for the design can be API and each one of them offers the particular specifications based on the material of manufacture, the operating pressure and the fluid type.

These standards provide for the use of additional thicknesses, the so-called "corrosion allowance” depending on the corrosivity of the working fluid, where it is proposed to typically add 1.27 mm or 3.2 mm of thickness due to the advancement of corrosion.

Likewise, as in most containers, quality standards are required in the welding processes, which which can be guaranteed through studies such as gammaging in longitudinal and circumferential seams of the trap.

On the other hand, considering that it will be a container subjected to a certain internal pressure, a test or test, generally hydraulic, is required to ensure its suitability for service. In addition, the access covers that allow access to the cleaning tool must be hermetic and must meet a series of requirements such as easy handling and fast closing.

Finally, the installation of the trap must have passage detectors, valves, pressure relief valves, manometers and bypass.

Utility

As we already mentioned, inspection and cleaning tools can be passed through the trap. One of them, the best known, is the scraper, “pork” or “pig”. Also, the famous "Smart pigs" that are "smart pigs" are inspection methods and non-destructive testing known as "In Line Inspection (ILI)”. When an ILI run is made, the pig is allowed to pass through the duct, providing for its cleaning since the sensor can get stuck with scales and in turn the tool results conform to the reliability there is in making data. The more accurate they are, the better the degree of knowledge about the status and condition of the pipeline. Likewise, the degree of cleanliness of the pipe helps to adjust the efficiency of the chemical products used, their doses and forms of application or even their replacement.

When cleaning tasks are carried out, it is called “mechanical pigging”, that is, a pig used for mechanical cleaning tasks. This allows the removal of solids and incrustations, since by friction it removes adhesions from the walls and by sealing, the scraper advances linearly in the pipe being pushed by the same fluid, which can generate a longitudinal compression effect that helps the force exerted on the walls, as in the case of the "polly pig”, polyurethane foam pigs.