Plugged Lines

Hot tapping is a process whereby a connection can be welded to a pipe or tank. In the case of a pipe, the flowing fluid will remove the heat. For tanks the heat is removed by the movement of the heated fluid (with tanks containing liquid, the work should always be done at least 1 meter below the liquid level). 

Hot tapping is inherently hazardous and should only be done when  

Process lines, piping, and valves frequently become plugged. Various techniques for avoiding the formation of pluggage and for removing pluggages safely are discussed in this section. 

If line pluggage is a recurring problem, it is best to try and identify ways in which the problem can be prevented from occurring. If that solution is not possible, then valves, drains, tees, and connections should be designed so that it is possible to remove the pluggage safely and with minimum time and expense. 

---

Pressurization due Stop transfer and de-pressurize before breaking to plugged transfer line and clearing plug lines. CCPS G-22 CCPS G-29... 

Material solidifies Monitor and control temperature in feed system or is too viscous, Heat trace and/or insulate lines and plugs lines. Potential for proper line break procedures exposure while Use personal protective equipment (PPE) correcting, proper lockout-tagout and confined space problem. entry procedures CCPS G-23 CCPS G-29 Fisher 1990... 

Suspended Solids None Suspended Solids is the measure of undissolved matter, determined gravimetrically suspended solids plug lines, cause deposits in heat exchange equipment, boilers, etc. Subsidence, filtration, usually preceded by coagulation and settling... 

Pressure can liave a significant impact on safety. Extreme pressures can cause severe metal stress, which can lead to a vessel rupture or explosion. High temperatures, plugged lines, and many other condiUons can cause increased pressure. 

Avoidthe possibility of pumping a liquid reactive material against a closed or plugged line. 

Wax-related problems are common throughout the petroleum product industry. Fuels and lubricants contain wax at varying concentrations. Filter plugging, line blockage, viscosity increase, and product haziness are all symptoms of wax formation within a fuel or oil. 

Emergency heating systems when a material could either freeze or become viscous, which would plug lines and prevent movement into a mitigation system. 

Loss of fuel gas to Heater. Hydrate formation plugging line Overpressure upstream system Local Tl PSV s on the system Install TSL on H-1 outlet and common alarm beacon ... 

Polypropylene was produced in three reaction trains on a location that employed nearly 300 workers. A recycle cooling line on a Reactor in Train A plugged with product slurry. This was considered a regular occurrence. Standard procedures to address this plugged line required mechanics to work under the direction of operators to rod-out the... 

Figure 3.3 shows some elements of piping. The essential elements are pipe diameter, couplings, sight tubes, line branches (tees, wyes), and elbows. Some systems such as conveying systems for carbon black may contain aerators to prevent line plugging. Lines are usually 1.5 to 8" in diameter and are made out of aluminum, steel, or stainless steel. The designer should keep the number of branches, valves, and elbows to a minimum. Each causes obstruction to flow and potential problems in operation. 

Thermowell with excessive thermal resistance (e.g., stainless steel thermowells) Partially burned out thermocouple Interference from heat tracing Plugged line to pressure indicator ... 

Flashing of liquids as they flow through an orifice meter Plugged line from process to DP cell ... 

Plutonium polymer. At low acidity and high temperature, plutonium forms a polymer that deposits as an insoluble solid film on the walls of process equipment. Polymer deposition plugs lines, fouls surfaces, and may result in unanticipated accumulation of a critical mass of plutonium. Figure 10.38 summarizes [M3] the results of investigations of the combinations of low acidity and high temperature that must be avoided if plutonium polymer formation is to be prevented. 

Job Safe Practice Parting flanges on plugged lines that may be pressurized Number 166 ... 

---