Sub Sea

Hoffer Meters in the Depths of the Ocean

It has long been known that some of the largest reserves of oil and gas lay below the waters of the world’s oceans. For the last several decades the relatively shallow coastal waters have been the center of activity to locate and extract these reserves. With the ever increasing demand for energy and the increasing price of energy, oil companies have been forced to look in deeper and deeper water to locate new reserves. Until the last few years, the limitation on how deep underwater a reserve could be tapped was the ability to build a fixed production platform structure tall enough and big enough to reach the ocean floor. This limited production to water depths of no more than a few hundred to just over 1000 feet. That is no longer the case. The invention of advanced subsea production systems, remotely operated vehicles (ROV’s) and floating oil and gas production facilities have now pushed the limitation on water depth out to the10,000-foot mark and soon beyond. Accurate flow measurement of a variety of fluids used in these subsea production systems located on the ocean floor and on the ROV’s used to service them at these extreme depths is critical to their proper and safe operation. Measurement applications include specially formulated hydraulic control fluids, drilling mud and sea water.

Hoffer Flow Controls is a leading supplier of highly customized flowmeters to meet the extreme conditions associated with working at depths to 10,000 ft or more. In addition to high internal operating pressures of up to 10,000 PSIG and more, the meters must withstand high external pressures created by the sea. These pressures can reach as much as 5000 PSIG. The temperature of the seawater to which the meters are exposed is often well below 32° F (0° C). The salt content of the seawater prevents the water from freezing but still reduces the strength of metals which must be taken into account. The need to transmit the flow signal to a remote input control device, either located subsea or on the surface aboard the production facility, requires the use of specialized electrical connectors to permit wiring interfaces. These connectors are often welded to the top of special risers that enclose the meter coil(See Illustration 1). This coil riser enclosure must also be able to withstand the high external pressure exerted by the sea and remain watertight.

Above all else, however, the flowmeters must be exceptionally reliable. Day-in and day-out the flowmeters must function accurately and reliably at these depths without routine servicing or maintenance. When a subsea system has to be serviced, it is a logistically complicated and financially expensive operation. Though scheduled servicing is required on the systems; an unscheduled service call due to a flowmeter failure is simply not acceptable. The extraordinary reliability of Hoffer turbine meters under these conditions has made them the preferred choice for many subsea system manufacturers.

Pictured in Illustration #2 is one of three custom-built Hoffer 4” flowmeters recently built for use on a new subsea system being developed for

Insertion turbine meters

provide multiple advantages when compared both to in-line turbine flowmeters and other types of flowmeter technologies. These advantages include low cost, negligible pressure drop, low installation costs, minimal potential points of leakage, and avoidance of high pumping costs. Additionally, the HP insertion turbine flowmeter can be specified for use in velocities up to 50 FPS. This allows pipeline companies to move a maximum amount of product in the shortest time possible.

Leak detection and pipeline integrity is not only essential to the bottom line for the pipeline company, it is an environmental issue. In California, in particular, Hoffer has supplied insertion turbine flowmeters for pipeline integrity verification. Many of the petroleum products being measured include the additive MTBE. Proper selection of the flowmeter seal is essential for any application, however, is sometimes more challenging with various additives factored into the equation. Hoffer has successfully specified and supplied the insertion turbine flowmeter for a wide cross section of pipeline applications.

Hoffer Meters in the Depths of the Ocean

operations at depths to 10,000-feet and beyond. These are perhaps the largest turbine meters ever built for operation at these depths. The meters feature a proprietary high-pressure clamp-type end fitting specified by our customer. They are rated and tested to internal and external operating pressures of 10,000 PSIG. The coil rise atop the meter is built from a smaller version of this same connector. It mates with a blind connector (not shown) to form the riser enclosure. In the upper portion of this riser enclosure, a HIT-1B transmitter is also located to provide a 4-20 mA output signal that is transmitted to a controller remotely located in another subsea enclosure. From concept to final product, these meters were designed, built and tested in 12-weeks, an astonishingly quick turnaround for such a highly customized product. Once again, when the pressure to perform was on, Hoffer delivered. and high pressure versions. The unit produces a frequency pulse output. Hoffer can supply either a pulse producing preamplifier or an analog signal converter with the HP meter. The recent introduction of the HIT-1 smart signal converter allows user to take advantage of the excellent repeatability of the HP flowmeter. This means that users can achieve ±0.25% linearity over a 10:1 flow turndown range when they specify the HIT-1transmitter with the HP insertion turbine flowmeter.

Whether your requirements for flow measurement take you to the depths of the ocean, the outer reaches of the Solar system or on plain Terra Firma, call on Hoffer. We have the experience to deliver the performance you need, when you need it.

Hoffer to Attend Upcoming Trade Shows

Over the next several months we will be very busy in preparation for the upcoming shows. We will be exhibiting at the ISA 2001 Show which will take place this year on September 10th through the 13th at the George R. Brown Convention Center in Houston, Texas. We will be located at Booth# 2725 if you are planning to attend. If you are located in or around this area and would like to attend, call us and we will send you a free registration. At the event this year we will be highlighting several products including our extended life turbine flowmeters with hybrid ceramic ball bearings, the Nova-Flow “Plug n Flow” flow computer, the New HIT-3 linearized pulse transmitter, and the upgraded HIT-2A rate indicator/totalizer with the same great features that made it so popular but now featuring infrared capabilities, output diagnostics, an improved LCD display, 20 point linearization and more. Stop by and see our new working demo featuring the Nova-Flow computer.

Annual Truck Mounted Cryogenic Proven Certification Seminar

Hoffer Flow Controls will conduct its Annual Truck Mounted Cryogenic Certification Seminar on September 20-22, 2001. The seminar offers hands-on training on Hoffer Ace Cryogenic Systems and calibrating with the Hoffer SY-14B proven. This type of training enables the drivers to operate and maintain their equipment much more effectively.