Grayloc® Closure Systems

Providing easy, quick, and safe access.


Our Closure Systems provide simpler and faster access to pressure vessels and other pressurized equipment by combining our Grayloc Clamp Connector with clamp supports and a hinged door. Suitable for use in extreme temperatures and pressures, the customizable systems can be oriented vertically or horizontally to meet your operational needs.


Well-suited for large diameter applications


Enable safe, rapid, and frequent access


Eliminate fugitive emissions


Technical Specifications

Nominal pipe size6 to 36 in, larger sizes available upon request
Design pressure ratingFrom full vacuum up to 60,000 psig
Design temperature range-423 to 1700°F / -253 to 927°C
HubNickel alloys, carbon, low-alloy, stainless and duplex stainless steels
Seal RingNickel alloys, low-alloy, stainless and duplex stainless steels
BoltingNickel alloys, carbon, low-alloy, stainless and duplex stainless steels
TrunnionNickel alloys, carbon, low-alloy, stainless and duplex stainless steels
Support plateNickel alloys, carbon, low-alloy, stainless and duplex stainless steels
Drive screwNickel alloys, low-alloy, stainless and duplex stainless steels
Hinge pinNickel alloys, carbon, low-alloy, stainless and duplex stainless steels
ASME B31.1, Power Piping
ASME B31.3, Process Piping
ASME B31.4, Pipeline Transportation Systems for Liquids and Slurries
ASME B31.8, Gas Transmission and Distribution Piping
ASME B31.12, Hydrogen Piping & Pipelines
ASME Section I
ASME Section VIII Div. 1
ASME Section VIII Div. 2
ASME Section VIII Div. 3
API 6A: Specification for Wellhead and Christmas Tree Equipment

Product Documents

Optional Features

Our self-contained, ready-to-install closure assemblies can be customized to meet your project and access requirements.

  • Seal ring retention system
  • Sight glass
  • Pressure sensor
  • Bolt shrouds
  • Temperature sensor
  • Adjustable hinges
  • Safety interlock systems
  • Hydraulic nuts for bolt tensioning
  • Zero pressure verification (vent valve)
  • Single drive screw (remote clamp layout)
  • Automated opening and closing
  • ASME code stamped

Typical Applications

  • Simplifies access to food processing vessels, including those used in supercritical applications
  • Provides easy, safe access in hazardous environments including fueling applications
  • Increases safety with fully automated, remotely operated opening and closing
  • Provides a customizable solution for integration into original equipment manufacturer designs
  • Provides safe access to pressure equipment requiring frequent internal access for cleaning or product removal
  • Ideal for use in areas where external lifting options and access are limited
  • Supports easy and quick launching and recovery of pipeline pigs
  • Enables simplified access and exceptionally quick opening and closing
  • Provides easy and quick access to vessels and other equipment with fewer personnel and no external lifting requirements
  • Enables safe, frequent access to vessels that require regular cleaning
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Field Inspection and Maintenance Services

Grayloc offers on-site inspection and maintenance services to ensure the integrity of our connectors and to facilitate the return of worn or damaged hubs to within factory specifications.

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