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Shaffer® NXT® RAM BOP


World Petroleum Supply stocks National Oilwell Varco the top industry manufacturer RAM Blow Out Preventers (BOP).

Shaffer® RAM BOP Family

Shaffer® NXT® BOP Blowout Preventer


After years of limited changes in the development of BOP design, National Oilwell Varco's line of Shaffer'" NXT BOP Systems offers the drilling industry improved drilling economics in a new generation of well control systems. This new generation BOP has changed the performance expectations for pressure control equipment, offering significant operational advantages and features.

The NXT includes XT'" "Boltless Doors" and a "No-Weld Cavity". Single, double and triple cavity models are available for working pressures of 5,000, 10,000 and 15,000 psi. The double and triple models save space and weight by combining two or three ram compartments into one unitized body. Lock options include Poslock®, Ultralock'", and Manual Lock systems. NXT BOPs are manufactured in accordance with API Specification 16A, Third Edition, June 2004 and NACE MR0175 per API Specification 16A, Temperature T20

NOV's Shaffer NXT BOP offers a number of benefits and has significantly improved safety and efficiency, with quick access using boltless doors.


Boltless Doors

National Oilwell Varco Shaffer® BOP Systems are unique in highlighting a means of significantly improving safety and efficiency in the critical path of activity. With the replacement of the large door bolts in ram BOPs Shaffer has eliminated the manual practice of using brute force to torque up a series of large bolts. With the elimination of the large doors bolts in these ram BOPs, Shaffer'" has eliminated the time-consuming practice of using hydraulic tools to manually torque-up multiple door bolts. There are a number of benefits with this development.

  • Reduced Weight (lightest BOP systems in the industry)
  • Reduced Height (smallest BOP systems in the industry)
  • Elimination of Manual Labor under time pressure
  • Elimination of cross threading bolts
  • Ram changes go from 4 hours to 40 minutes (15 Minutes with an ARC® Automated Changer)

Door Operating Principle

The NXT "Boltless Door" assembly is mechanized using hydraulics to lock, unlock, open and close the door. The lock and unlock process is done with hydraulic cylinders mounted on the doors used to engage and disengage a locking bar system. These load bearing lock bars, housed in the door grooves, lock the door and body together.

Hydraulic System

Hydraulic power to operate a Model NXT ram BOP can be furnished by any standard oil field accumulator system. Hydraulic passages drilled through the body eliminate the need for external manifold pipes between the hinges. Each set of rams requires only one opening and one closing line. There are two opening and two closing hydraulic ports, clearly marked, on the back side of the BOP. The extra hydraulic ports facilitate the connection of the control system to the preventer.

A standard hydraulic accumulator unit will close any model NXT ram with rated working pressure in the well bore.

Shaffer® Ram BOP Components

18-3/4” BOP Systems

The Introduction of the NXT® Ram BOP was initially in the 18-¾”, 15,000 psi size. This system was designed to enable a stack height and weight package similar to a 13-5/8” BOP configuration and provide the capability of eliminating the dual stack drilling system with a through bore wellhead connector. Actuation of the boltless door mechanism is available in two configurations:

  • Remote or door mounted hydraulic operation
  • Simple manual mechanical door actuation at the ram door.
Shaffer® NXT® BOP Blowout Preventer

No-Weld Cavity

Shaffer's no-weld cavity feature, introduced in the SLX model ram blowout preventer, is standard on the NXT ram blowout preventer. This no-weld cavity feature allows upgrade of the BOP to "as new" condition by introducing replaceable parts to the cavity. Post-weld heat treatments and extensive in-shop repairs are thus eliminated. The no-weld cavity has a replaceable seal seat, a replaceable skid plate and replaceable side pads.

NXT® Lock Options

NXT Ultralock II Ram Locking System

The Ultralock II locking system incorporates a mechanical locking mechanism within the piston assembly. This locking system is not dependant on closing pressure to maintain a positive lock. It uses flat tapered locking segments carried by the operating piston which engages another stationary tapered shaft located within the operating cylinder.

The system needs no adjustments, no matter the size of the pipe rams. Different size or type ram assemblies can be freely interchanged.

Only one hydraulic function is required to operate the cylinders open/close function and the locking system. The system automatically locks in the closed position each time the piston assembly is closed. Once the operating piston is closed on the pipe, the locks are engaged until opening pressure is applied. Only hydraulic pressure can unlock and reopen the preventer.

NXT Poslock (Shear Operator) System

NXT preventers equipped with Poslock pistons are locked automatically in the closed position each time they are closed. The preventers will remain locked in the closed position even if closing pressure is removed. Open hydraulic pressure is required to reopen the pistons. The hydraulics required to operate the Poslock are provided through opening and closing operating ports. Operation of the Poslock requires no additional hydraulic functions, such as are required in some competitive ram locking systems.

NXT Manual-Lock Systems

Manual-lock pistons move inward and close the rams when closing, hydraulic pressure is applied. If desired, the rams can be manually locked in the closed position by turning each locking shaft to the right until it shoulders against the cylinder head. Should hydraulic pressure fail, the rams can be manually closed and locked. They cannot be manually reopened.

Manually locking shafts are visible from outside, and provide a convenient ram position indicator. Threads on the manual locking shaft are enclosed in the hydraulic fluid and are not exposed to corrosion from mud and salt water or to freezing.

Manually locking shafts are visible from outside, and provide a convenient ram position indicator. Threads on the manual locking shaft are enclosed in the hydraulic fluid and are not exposed to corrosion from mud and salt water or to freezing. See RAM BOP Lock Option Section.

See RAM BOP Lock Option Section

Note that rams are priced separately from the BOP, and the customer is asked to specify the ram sizes to be installed in the cavities at the time of order placement.

NXT Shear Booster Operators

Three styles of shear booster operators are available. The standard NXT body is available with the Super Booster with a Poslock'" system aided by two tandem boost pistons. This produces the force required to shear today's high CHARPY drill pipe. The 14" x 14" (35.6 mm x 35.6 mm) compact shear booster design incorporates a Poslock system with a single 14" diameter boost piston. The 14" x 14" compact design is also capable of shearing today's high CHARPY drill pipe with 3,000 psi operating pressure. The preferred-offering extended NXT body incorporates a 22" shear operator with a 5,000 psi working pressure (see figures) and Poslock® system. This operator is designed to shear the latest offering of 5"Va" high CHARPY drill pipe, large diameter casing, and the future offerings of larger diameter (6"Va") high CHARPY drill pipe without a booster. While capable of operating with a 3,000 psi hydraulic supply, the 22" operator reaches full capability when a 5,000 psi hydraulic system is used as its supply. A 3,000 psi hydraulic system provides similar shear force to that of the Super and Compact booster operators.

Control Manifold Option

Hydraulic door functions are operated through a control manifold assembly. The assembly is mounted to a plate for convenient customer installation.

Test Cavity Option

The lower BOP ram cavity may be ordered "inverted" to seal on pressure above the ram assembly. This optional configuration of the ram cavity permits surface pressure testing of the BOP without the need to trip a test plug. Note: The test cavity is not bidirectional; that is, it does not seal with pressure below the rams.

Shaffer® NXT® BOP Blowout Preventer - Closing Pressure

ARC® Ram Changing System

Shaffer® NXT® BOP Blowout Preventer - Closing Pressure

The Automated Ram Changing System (ARC®) has the potential to dramatically reduce, and possibly eliminate, lost time incidents by removing all hands-on activity involved in changing rams. Manpower may be reduced by 50% allowing for ram changing activities to be performed by a crew of 1-2 instead of the 4-5 conventionally required. Safety of rig personnel and cost savings realized are just some of the benefits of using the ARC®.

A ram-changing arm quickly and accurately retrieves and replaces rams in minutes, from a simple removable storage magazine.

Features of the ARC® include:

  • Magazine Capacity: 2 or more
  • Configurable to jack-up, platform or subsea applications.
  • Reduced ram change time, and lower, costs, when ARC® is combined with NOV"s Shaffer™ XT boltless doors.
  • Removes requirement for rig personnel to perform the dangerous task of ram change out manually.

Operational Benefits

  • Extended length of subsea deployment
  • In deep water, saves time and money by not having to pull the stack and run stack back to bottom
  • Remote subsea ram change
  • Redundant cavity not a necessity
  • Fewer cavities equate to lighter, more compact stacks
  • With ram reconfiguration as an automated method, the use of more reliable fixed bore pipe rams can be increased. This means increased reliability sealing at higher pressures, longer ram rubber life, and greater hang-off capacity.
  • Ram-to-Ram stripping or snubbing becomes practical because of the ability to replace worn ram rubbers.


  • Reduction of manpower and equipment when using automated bonnet access system
  • Torque wrenched and hammer wrenches no longer necessary.
  • Rig hands are free to work in less hazardous areas.
  • Space constraints on surface and jack-up rigs make manually changing out rams a labor intensified and dangerous task. By using this system, manpower is reduced and safety is improved.
Shaffer® NXT® BOP Blowout Preventer - Closing Pressure

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