{"id":1078,"date":"2026-02-09T22:55:02","date_gmt":"2026-02-09T22:55:02","guid":{"rendered":"https:\/\/hydrocarbon.sbs\/?p=1078"},"modified":"2026-03-25T12:26:23","modified_gmt":"2026-03-25T12:26:23","slug":"use-a-seven-step-procedure-to-mark-piping-cmls","status":"publish","type":"post","link":"https:\/\/petrostreet.com\/main\/use-a-seven-step-procedure-to-mark-piping-cmls\/","title":{"rendered":"Use a seven-step procedure to mark piping CMLs"},"content":{"rendered":"\n

Piping is considered one of the most valuable assets in any hydrocarbon processing facility. Many meters of piping run through these facilities, transporting process fluid from one unit to another. The integrity of piping systems is as important as that of any other asset in the facility; however, when studying piping systems of
different sizes, metallurgy and lengths, it is important to consider inspection plans that are not only effective but also efficient with respect to the effort required. Marking more condition monitoring locations (CMLs) than necessary wastes time and effort, but marking far fewer CMLs than needed puts piping integrity at risk. Several guidelines are available to define the CMLs on a given piping system; however, the plant inspector has the ultimate control over defining, inspecting and redefining the CMLs throughout the piping life. This is a continuous process (FIG. 1), and balance can be achieved only after at least one full round of design life is finished with no loss of process containment. Data from similar operators may help achieve a balance to the piping inspection, which is normally the first step in defining CMLs for any piping system. A stepwise approach in defining, inspecting and redefining CMLs on any piping system is detailed in the following sections.<\/p>\n\n\n\n

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FIG. 1. General work view of a piping inspection.<\/p>\n\n\n\n

Step 1: Data from similar operators.<\/h3>\n\n\n\n

Sharing data between industries and companies worldwide is not uncommon, but it can be difficult to organize. Nonetheless, if a data-sharing arrangement can be made, information from similar service
operation can help in many ways. Of significant usefulness are comparable CMLs marking data for piping systems in similar service. These provide a quick start for other operators to launch this continuous process. If already normalized for a given piping system at a hydrocarbon processing facility, verified CMLs can save massive effort for a new operator. However, if such data is not available or not easily obtained, then this step can be skipped.<\/p>\n\n\n\n

Step 2: Identification of credible damage mechanisms<\/h3>\n\n\n\n

Information on credible damage mechanisms must be obtained before starting work to define the CMLs on any piping system. If a risk study has already been performed for the facility, then this document may contain the relevant information.<\/p>\n\n\n\n

Step 3: Define inspection tasks<\/h3>\n\n\n\n

Inspection tasks must be defined after information on credible damage mechanisms is made available. These inspection can provide a way forward for marking appropriate CMLs. In most cases, inspection tasks for piping include measuring the wall thickness to identify different forms of corrosion. Most CMLs are marked to perform ultrasonic inspection tasks.<\/p>\n\n\n\n

Step 4: Corrosion rate determination<\/h3>\n\n\n\n

When designing a piping system, an initial design corrosion rate is always considered to define the lifespan of a piping system. This critical information defines the corrosion allowance. For all piping systems, the initial design corrosion rate must be tabulated to determine the actual corrosion rate.
To determine the actual corrosion rate, initial marking of CMLs should be done only on baseline thickness locations, if available. If baseline thicknesses have not been measured, then CMLs should be defined at bare minimum locations to enable the inspector to determine the actual corrosion rate.
The initial inspection frequency can be increased so that this exercise can be completed. A round of three inspections should be sufficient for accurately calculating the corrosion rate of any piping system.<\/p>\n\n\n\n

Step 5: CMLs placement<\/h3>\n\n\n\n

An inspector must evaluate the placement of CMLs based on several factors:<\/p>\n\n\n\n