Accumulators have many uses in the oil and gas industry. Steelhead Composites’ lightweight accumulators are an ideal solution for offshore and remote locations where weight is a factor. Our accumulators are one-third to one-quarter the weight of traditional steel accumulators, while offering the same functionality. Consequently, several primary benefits present themselves for weight-restricted applications in oil and gas industry where delivery access is challenging, specifically offshore drilling rigs or remote sites.

Steelhead composite accumulators also have a larger diameter 12 inches (30.5 cm) and can be up to 10 feet (3 meters) in length with pressures ranging from 3,000 psi (207 bar) to 6,000 psi (414 bar). This flexibility allows for greater design flexibility, fewer accumulators in a space, further reducing the weight at a notable cost savings.




  • Emergency energy storage
  • Riser tensioner system for offshore drilling platform
  • Fluid volume compensation due to temperature fluctuations
  • Cushioning of pressure shocks from sudden switching of valves
  • Pulsation and vibration dampening for reciprocating pumps
  • Compensation of leakage oil in machinery

An accumulator is essentially a pressure vessel that contains a combination of gas and hydraulic fluid under high pressure. There are several advantages to using high strength and low density composite materials in fabricating these pressure vessels:

  • Composite pressure vessels are much lighter than comparable steel ones. Depending on the proportional amount of carbon fiber overwrap and aluminum liner used to manufacture composite accumulators, they will weigh between one-third and one-quarter of a comparable high-strength steel accumulator. The lighter mass of the accumulators translate into improved fuel efficiency and easier retrofit of the hydraulic hybrid vehicles.
  • The rupture characteristics of composite pressure vessels are significantly more benign than those of steel pressure vessels. When a composite pressure vessel is punctured, there is no catastrophic rupture. Aluminum lined composite pressure vessels are also designed for leak-before-burst failure mode when subjected to repeated cycles.
  • Steel pressure vessels are susceptible to galvanic corrosion, especially in a salt air environment. In contrast, composite materials are inherently corrosion resistant and provide longer life to the accumulators in vehicular use.
  • Composite pressure vessels have a long and safe life expectancy. Because of the high fatigue life of carbon fiber composites, these vessels can provide years of safe operation.

Steelhead Composites has taken a grounds-up approach to designing a composite accumulator. Some of its unique features are:

  • Traditional steel accumulators have inside diameter of 8 inches (200 mm). Steelhead has optimized the size of the composite accumulators to integrate with hydraulic hybrid vehicles and is currently offering these vessels in 10 inch (250 mm) internal diameter. These vessels allow for more internal volume and energy storage capability for a given vehicle chassis length. Steelhead has exclusive ownership of the tools and molds required to produce bladders, aluminum liners and port fittings for these larger diameter accumulators.
  • Steelhead composite accumulators are approximately 1/4 to 1/3 the mass of their steel counterparts, for a given operating pressure and internal volume. Lighter mass translates into correspondingly higher energy density (energy stored per mass) and power density (power generated per mass) capability for these accumulators.
  • The operating pressure of Steelhead’s composite accumulators is 6,000 psi (414 bar). This is higher than the industry standard operating pressure of 5,000 psi (350 bar) offered typically in steel accumulators.
  • Composite accumulators offered by competitors are typically adapted from heritage designs of vessels meant for gaseous storage and have relatively small port openings, 2.5 inch (63.5mm) or less. Steelhead’s composite accumulators have been designed with a larger port opening on the hydraulic end, 3.5 inch (89 mm) diameter or larger. A large port opening poses a significant design challenge for the composite vessel. Steelhead has overcome this challenge through extensive design iterations and proprietary technology to strengthen the polar opening. The large port opening not only allows for easy installation of the bladder, but also accommodates a bladder with higher wall thickness that results in low permeability and longer life span for the bladders.