How to check the unqualified tightness of oil and gas recovery system? Common leakage points and treatment methods

How to investigate if the sealing of the oil and gas recovery system is not qualified? Direct answer: Airtightness is the basic indicator of the entire system, and any air leakage will lower the overall test results. The investigation will be carried out in the order of "from the refueling machine to the tank area" - recycling copper pipes and joints inside the refueling machine, recycling pipeline valves and flanges, tank area manholes and oil measuring ports, oil discharge ports and exhaust ports, point by point, and the leakage points are basically in these types of positions. The unqualified airtightness affects all testing items, including liquid resistance, gas-liquid ratio, and emission concentration, all of which are based on the premise of system airtightness. The leakage point should be blocked first, and the subsequent indicators will have a basis for discussion. This article clarifies the list of common omissions and their handling methods, and follows the self inspection and rectification procedures for the site.

Why is airtightness tested first

Tightness testing is used to perform a physical examination on the entire system: after applying pressure or vacuuming to the system, the pressure change is observed. If the pressure drop exceeds the limit, it is judged as unqualified. Its value lies in exposing hidden dangers scattered on tens of meters of pipelines at once - underground pipelines are invisible and intangible, it is not realistic to excavate every meter to find leaks, and the airtightness test first uses data to tell you that the system has leaks, and then collects the network according to the probability list of leak points. The test should be conducted during the period without oil unloading operations. The status of the ball valve at the oil unloading port and the opening and closing of the breathing valve will affect the reading. If the test conditions are not correct, a qualified system will also be misjudged. Before retesting, check the conditions again.

List of Common Leakage Points

The high-risk locations for leakage are ranked by probability: the recycled copper pipe joints and valves inside the fuel dispenser are subject to frequent vibration and maintenance, and it is common for seals to loosen and leak; The flange and threaded interface of buried pipelines, gasket aging or construction defects causing leakage, and the buried interface itself is not recommended; Manhole flange and oil measuring port, aging sealing gasket or loose oil measuring port cover; At the explosion-proof pipe threading point between the power line of the submersible pump and the signal line of the liquid level instrument, the rubber sealing plug does not match the wire diameter or has aged and lost elasticity, causing oil and gas to flow out through the gap; The vacuum pressure valve at the top of the exhaust riser is exposed to wind and sun all year round, and the sealing surface is corroded and cannot be tightly closed. Go through each item one by one, and most of the omissions are within this list.

The order and techniques of investigation

In addition to point by point inspection, several techniques can save a lot of effort: first look and then test. There is a high probability of leakage in areas with oil stains, rust marks, and strong odors, and visual inspection is necessary before installing the instrument; Positive pressure soap solution method is used to deal with exposed joints. Apply soap solution and observe bubbles every few tens of seconds; Segmented pressure maintenance is used to deal with buried sections. The pipeline is divided into several sections according to valves, and each section is isolated and maintained for pressure. The pressure drop section is the suspected section, and the range is gradually reduced; Don't rush to finish repairing a point. Since the system has been leaking and similar interfaces have similar aging levels, it is more cost-effective to inspect and replace them in batches rather than repairing one by one. Record the investigation by point, compare the pressure drop changes during the next inspection, and see the hidden danger trend earlier.

Comparison of processing methods

Investigation and rectification steps

1. After confirming the testing conditions, retest and lock the leakage range;
2. Check point by point from the fuel dispenser end to the tank area according to the checklist;
3. Segmenting and pressure reducing the suspicious pipe section;
4. Replace the sealing components and select according to the material requirements;
5. After rectification, retest the overall airtightness;
6. Archive the location and handling records of the leakage points.

Frequently Asked Questions

How often is the airtightness tested?

According to the testing cycle and self inspection plan, the common practice is to conduct annual testing and simple positive pressure observation during daily inspections; After repairing pipelines or replacing equipment, conduct additional testing at any time. Don't wait until the annual inspection to discover the problem.

Can applying soapy water detect leaks?

Can identify the leakage points of the installed joints and valves, apply soap solution under positive pressure to observe bubbles, simple and effective; The buried section cannot be inspected, so it is still necessary to rely on segmented pressure maintenance and positioning. The combination of the two methods is more efficient.

How long does it take to retest after the leak is repaired?

After replacing the seal, wait for the rubber material and gasket to be compacted and stabilized before retesting. Usually, retesting is arranged within the testing condition window after the rectification is completed; If the retest is still not qualified, it indicates that there are still missing points. Continue to narrow down the range by holding pressure in sections.

This article is organized by Luoyang wohong petrochemical equipment co., ltd. the company provides design, manufacture, installation, commissioning and operation and maintenance services for oil and gas recovery equipment, solvent recovery devices and buried composite pipe networks at gas stations, oil depots and chemical enterprises. if you need scheme configuration or on-site investigation, please contact and exchange.