HJ4 Mechanical Seals Provide Exceptional Performance in High-Pressure Oil Pipeline
In 2004, when a Chinese drilling company needed superior seals to perform under strenuous conditions, they turned to EagleBurgmann. The HJ4 Mechanical Seals series for high-pressure crude oil pipeline pumps proved a perfect solution, even under demanding conditions.
Often several liquid-lubricated dual mechanical seals are installed in a production plant, and there are various possibilities for supply systems that users can choose from. A dedicated supply system can be provided for each dual mechanical seal, or several dual seals can share a supply system. Deciding which option is best is not always easy, and this article is intended to provide guidance during the decision making process.
The sealing chamber between the product and atmospheric side must be completely filled with a clean medium to ensure that a dual mechanical seal functions properly. A so-called supply system delivers the medium, and it is called a barrier system if the supply medium pressure exceeds the process pressure. Barrier medium or fluid is the name that is used for the supply medium or fluid.
The Republic of Sudan is a country in northeastern Africa with access to the Red Sea. With an area of about 965,000 square miles, it is the largest country in the African continent and the Arab World. The Sudan has various mineral resources, but production of oil, its main export, is increasing dramatically (38.1 % growth from 331,000 barrels per day (bpd) in 2006 to 457,000 bpd in 2007). The country has estimated reserves of 6.6 billion barrels of oil. China, the world’s second largest oil consumer, buys some of its oil from Sudan. In 1984, the Chinese began to explore oil in the African Continent, particularly in Sudan. One of China’s largest oil companies was granted an oil production license and has been investing in Sudanese oil fields ever since.
In 2004, the company awarded a multi-million dollar contract to a major German pump manufacturer for several high-pressure pipeline pumps.
Process and Equipment
A 435 mile pipeline runs from the oil fields near Baleela via the Khartoum Refinery where the high viscosity crude oil is processed and then forwarded through the pipeline to the Port of Sudan for export to China.
Six pumping stations keep the crude oil flowing smoothly through the pipeline. High- pressure twin screw pumps were commissioned at Pump Station I beginning in 2004, and subsequently, the oil company decided to install similar pumps at stations III and IV. The following equipment is needed at each pump station:
- Three pumps, each driven by an eight-cylinder diesel engine
- One cooling system for each diesel engine and pump
- One automatic control unit per pump
- One compressor per pump station to start the engines
Considerable expertise was involved in the design of the diesel engines and systems that have to operate at ambient temperatures up to 136 °F at an altitude of 2,250 feet above sea level. Components must be designed to compensate for losses that occur as a result of climatic conditions to ensure that performance. The pumps transport 16,000 to 30,000 barrels per day (bpd) at differential pressures of up to 97 bar. Each twin screw pump has two rotating shafts with two seals per shaft; thus four mechanical seals are installed in each pump. The sealing solution had to manage some very challenging conditions:
- Medium: crude oil
- Viscosity: = to cSt
- Suction Pressure: 58...725psi
- Temperature: 84° – 158°F
- Speed: 440 - 1,240 RPM
The EagleBurgmann HJ4 Seals Solution>
Our seals have been selected for this very demanding application. Single HJ47 series seals are installed on all of the pumps:
A total of 300 seals in five different sizes have been supplied. The rugged HJ component mechanical seals are balanced and have multiple springs. As the outboard springs do not come into contact with the product, no clogging occurs. Large clearances between the seal rotor and stator enhance drainage of high-viscosity leakage. The rotating seal face has a smooth process side contour and mates with a stationary seat.
The material combination Q3Q2VGG1 was selected. The face material pairing is Buka 30 vs. Buka 20. The secondary seals are made of Viton®. 1.4571 is used for the springs, and all other parts are made of 1.4462. A chrome oxide coating is applied to the metal component in the area of the dynamic O-ring.
Seal Successful installation and Performance
Three flights from Frankfurt-Hahn Airport in Germany were needed to transport the pumps, engines, etc. to Khartoum. The Chinese customer took possession of the systems in Khartoum and transported them by heavy vehicle to the final destinations. Teams sent out by the pump manufacturers kept an eye on the installation work and provided on-site training.
The pumps have now been in operation for five years. There is currently no other comparable screw pump installation anywhere in the world. Despite the adverse conditions, there have been no problems on the project. Seals and pumps mastered the difficult start-up conditions and showed an outstanding sealing performance.
For more information, please contact Kent Prichard, Territory Manager at firstname.lastname@example.org.