Inventive High Pressure Water Jetting
Many innovative alternatives - a new approach to cleaning heat transfer equipment
Inventive High Pressure Water Jetting
Many innovative alternatives - a new approach to cleaning heat transfer equipment
The specialist engineering consultancy of one of the world’s largest and oldest oil companies approached Tube Tech to ask if the company could carry out a fast clean on a failing refinery flare line in Germany, as a major shutdown was imminent. Tube Tech visited the site, carefully reviewed the task and surprised the client when they expressed the opinion that not only could the line be cleaned quickly, but it could even be done on-line! After lengthy and thorough planning, the line was successfully cleaned on-line and the back pressure in the line reduced to safe operational levels.
The Germany-based facility of this global oil company refines crude oil and produces a variety of hydrocarbon products, including ethylene, propylene, benzene, toluene, xylenes, and methanol. Combustible waste gases from all processes are offloaded into a single flare line for burn-off.
Back pressure had been building up in the 150 metre refinery flare line, as resistance to flow increased, due to the line being restricted approximately 40% overall by pyrophoric and sulphurous sludge deposition. The client’s own inspections suggested there were substantial sections of the pipeline badly restricted by this soft, mud-like sludge. Taking the flare line off-line for cleaning meant that the entire refinery would have to shut down, the operational and cost implications of which would be substantial, as any refinery operator will know. The client hoped therefore to limit any such impact if the clean could be accomplished during the shutdown.
TTIL surveyed the flare line. The client provided digital images, isometrics and inspection records. Tube Tech Technical Director, Mike Watson – renowned for his inventive approach – said he could clean the flare line on-line and put the idea to the client, whose engineers had recommended several companies for tendering. Tube Tech was the only one to offer this radical and surprising solution. If it could be achieved, while addressing all safety issues, it would be a world first for Tube Tech and the oil industry. The flare line clean could then be taken out of the shutdown and be done at the client’s convenience.
After a few months of meetings and detailed exchanges of information to establish project viability, Tube Tech offered to demonstrate Mike’s ideas on a full-scale mock-up of key sections of the flare line at its UK operations centre. The client’s consultants came to the UK, and witnessed a successful on-line trial, which demonstrated multiple fail-safes. Tube Tech’s bespoke seal coped with temperatures and pressures inside the flare line and prevented oxygen and spark ingress and the escape of toxic gases. The major technical difficulty was to design seals to access 25mm valve ports located at intervals along the length of the flare line.
Ultimately, only two points of entry were used. Cleaning would be carried out using pulsed high-pressure jetting lances designed to be heat and scratch resistant when fed into the small 25mm entry points.
All three systems devised for the project were trialled on the life-sized mock-up. Locating the deposits and establishing their level and density before cleaning was carried out by Tracerco, using gamma ray-based inspection during and after cleaning. Intrinsically-safe video probes visual inspection were used by Tube Tech through the 25mm ports to take digital images before and after cleaning.
The objective was to reduce the deposition level within the flare line by removing as much sludge as possible, to level the remaining deposit and achieve an 80% cleanliness level in order to reduce back-pressure. Some entry points turned out to be corroded shut or obstructed by weld intrusion, but Tube Tech’s ‘design-on-the-run’ reputation came to bear and equipment was modified to accommodate this unforeseen additional challenge.
A hot tapping service was on standby if more access was needed, but it was not required. With cleaning underway, some very good reports came back from the inspectors and in just five days the cleaning standard had been achieved.
Mike Watson: “Based on the client’s sample analysis, we came prepared for soft, mud-like deposition. Actual samples found during removal were concrete-like lumps, commonly known as ’sulphurcrete’ and not just sludge! We were, however, still able to wash loose concretion downstream to an interceptor tank. Whilst our objective had been achieved, we offered to return with appropriate equipment and a personal guarantee to all remaining concretion at some future date.”
Mike concluded: “This was the first time an on-line clean of a flare line had been accomplished. We have already designed more powerful equipment, capable of tackling any unexpected deposits, just in case another similar opportunity presents itself anywhere in the world. A considerable digital video archive of information and knowledge was built up during the exercise, which means we can repeat the exercise any time in the future.”
Clients can be contacted via Tube Tech for references.
Flare Line Cleaned "ON-LINE!" avoids Refinery Crash
Flare Line Cleaned with Nitrogen
Flare Line Cleaned Without Water Jetting
