Loading Arm

OPW offers the most complete line of loading arm systems and loading-rack equipment for today’s bulk loading and unloading requirements. Loading arm systems allow the transfer of gas or liquefied gas from one tank to another through a pipe system. When transferring gas, you will need both a bottom and top loading arm. Whether the application involves tank trucks, railcars, drums or totes, and the moving of petroleum products, liquefied gases, asphalt, solvents or hazardous/corrosive chemicals, OPW Engineered Systems is the preferred loading arm system choice worldwide.

Top Loading railcars and trucks continue to provide an efficient and cost effective method to load and unload in many situations.

A loading system should have sufficient horizontal range to reach the farthest compartment without re-spotting the vehicle. Sufficient vertical movement and drop-pipe lengths to service vehicles of varying heights is also necessary. A properly designed top loading system can provide protection and achieve this requirement. Top loading arms can also be used for tight-fill, vapor recovery, marine and other applications when used with specially designed and engineered components, such as vapor plates, tapered hatch plugs, and inflatable hatch seals.

Special top loading arm designs can also be supplied with a wide range of valves, fittings, and instrumentation equipment.

OPW Bottom Loading Arm Systems are ideal for loading and unloading petroleum products, chemicals and liquefied gases, and offer numerous benefits over conventional top-loading systems:

  • Improved safety since operator remains on the ground during loading/unloading
  • Quicker connections reduce overall loading/unloading time
  • Bottom loading systems create less turbulence in the tank, reducing the danger of generating static electricity.
  • Bottom loading reduces vapors and the system can be adapted to also recover displaced vapors
  • Tanks can be filled faster and several compartments can be loaded simultaneously
  • Bottom-loading islands are simpler and cheaper to build than top-loading racks

The slide sleeve type loading arm incorporates a slide-sleeve assembly that telescopes in and out to adjust for variations in the distance from the loading rack to the tank truck. It is used primarily in small bulk plants and terminals for top loading fuel oil or other petroleum products. This cost-effective loading arm is time-tested as a practical method of locating the drop tube accurately and easily.

Quick and Dry Disconnects

OPW Engineered Systems offers the most comprehensive line of dry disconnect products in the industry. Our line of dry disconnects include Drylok™, Kamvalok® and Epsilon®, all suitable for a broad range of hazardous liquid applications. Dry disconnect couplings have been proven as a successful technology to help protect workers and the environment in the transfer of hazardous materials. Our dry disconnect couplers ensure against accidental spillage of liquids. If your product is corrosive, toxic, caustic or otherwise harmful, OPW Engineered System’s family of high-performance dry disconnect couplings help reduce the hazards associated with the transfer of these products.

OPW Engineered Systems offers a comprehensive line of quick disconnect products in a wide variety of sizes and configurations. Kamlok® is the world’s most popular cam and groove. The name is synonymous with quick disconnects and has set the industry standard for safety and ease of use. Autolok® quick disconnects utilize a self-locking system to provide an added level of safety.

Swivel Joints

OPW manufactures swivel joints for a broad range of uses in the chemical, petroleum, petrochemical, refining, mining, distilling, brewing, ink and paint industries, as well as farm irrigation and fertilizing. Design, plant and maintenance engineers use OPW swivel joints in flexible piping systems, loading arms, hose reels, sewer rodding and wastewater treatment equipment, and various types of process machinery. They also use our swivel joints in machine tool coolant transfer, drum filling applications, and in a variety of in-plant fluid and dry bulk transfer applications. 

Versatility is the key to OPW swivel joints. They make it possible for you to use rigid metal piping for loading and unloading fluids and dry product under pressure or vacuum without the difficulty or danger of handling heavy, cumbersome hoses. 

Swivel Joint Design Features 

  • Tight Seals
  • Protected Bearing Chamber
  • Long-Life Bearings
  • Easy Lubrication
  • No Field Adjustment Necessary 

Designed for Safety

Our design efforts are supported by a state-of-the-art CAD system for faster, more accurate responses to your technical requests. OPW swivel joints are durable, reliable, easy to operate and maintain. Available in stainless steel, cast steel, fabricated steel, ductile iron, aluminum or bronze, we meet your most demanding specifications. Our special capabilities include split flange, jacketed, lined and coated.

Available in a variety of materials, sizes and styles to meet virtually any application.

  • Sizes: 3/4” to 12”
  • Standard Materials: Aluminum, Bronze, Carbon Steel, Ductile Iron, 316 Stainless Steel
  • Standard Seals: Buna-N, Fluorocarbon, PTFE, EPDM, Neoprene, Kalrez®
  • End Connections: FNPT, 150/300 ANSI Flanged Ends, Butt/Socket Welds

Metal Options

  • Aluminum (ASTM B26, A356 T6)
  • Bronze ( ASTM B62-83600)
  • Carbon Steel (ASTM A105)
  • Ductile Iron (ASTM A-536)
  • Stainless Steel (ASTM A351-CF3M/CF8M)

Seal Options

  • Buna
  • Fluorocarbon
  • PTFE
  • EPDM
  • Neoprene
  • Kalrez


Lubrication plays an important role in the life expectancy of a swivel joint. OPW has done extensive research to determine the best lubricants for our products. Our standard is a High Performance Synthetic Lubricant (OPW part # 880-0089).

  • Specially formulated to reduce friction & wear.
  • Requires only annual lubrication
  • Will not drip, melt or carbonize
  • Complies with FDA regulation 21CFR178.3570
  • Temperature Range -40F – 750F (-40C – 399C)
  • Not for use with EPT/EPDM Seals. EPT/EPDM seals require the use of OPW 885-0083 lubricant.

The Endura™ Dual Split Flange (DSF) swivel joint from OPW® Engineered Systems represents the best in swivel technology. Specifically designed for the transfer of hazardous materials such as acids, solvents, petrochemicals and other toxic fluids, Endura™ sets the standard in Loading Arm Swivel performance.

  • Standard Sizes: 2 in., 3 in., 4in.
  • Standard Materials: Carbon Steel, Stainless Steel
  • Standard Seals: Buna-N, Fluorocarbon, PTFE, EPDM, Neoprene
  • End Connections: FNPT, 150/300 ANSI Flanges, Butt Weld

Process Products

Dollar for dollar, sight flow indicators are the most cost-efficient and effective way to visually monitor the flow of fluids and to determine where, if any, problems exist at certain points along the industrial process line. OPW has been manufacturing sight flow indicators for over 60 years. Our experience has led to many innovations in design and manufacturing, making VISI-FLO® the most thoroughly-engineered Sight Flow Indicator on the market. VISI-FLO’s are available in two series: the Standard 1400 Series, and the 1500 High-Pressure High-Temperature Series.

Standard Features 

  • Exclusive 3-Year “No-Leak” Guarantee – VISI-FLO’s innovative radial seal creates a constant and uninterrupted sealing force between the body and outside diameter of the glass lens. This sealing method provides a longer lasting and better seal than conventional flat seals.
  • Maintenance-Free Design – VISI-FLO’s unique, bolt-on-body design requires no special maintenance or torquing sequence be followed to prevent leaks. This results in a safer, more reliable sight flow indicator than those units using tie rods to fasten lens and seal to body.
  • Dimensionally Interchangeable – “FJP” Flanged VISI-FLO®s feature end-to-end dimensions that match Jacoby-Tarbox and Penberthy and other manufacturers’ units. “FJP” units are available in 3/4″, 2″, 3″, and 4″.


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