IMCA Publishes Acrylic Plastic Viewports Guidance

press release
Thursday, February 09, 2012

Acrylic plastic viewports in diving systems have been in satisfactory use for a number of years. However, the development of testing them by polarized light showed that there are various misconceptions about them.


The International Marine Contractors Association (IMCA) has just released updated guidance on the topic. An initial guidance note which sought to correct these misconceptions was initially prepared as AODC 030 in 1986 following advice from Det Norske Veritas (DNV). Now a revised document has been produced by IMCA through the Safety, Medical, Technical & Training Committee of its Diving Division Management Committee as part of its planned phased review of AODC guidance notes, which are then issued as IMCA guidance.
 

“Acrylic viewports are used in many pressurised systems under a variety of conditions world-wide and this document has been produced to provide general guidance,” explains IMCA’s Technical Director, Jane Bugler. “It includes additional guidance on deterioration compared to its predecessor, and identifies a reference document which perfectly complements it.
 

“That document is the ASME ‘Safety Standard for Pressure Vessels for Human Occupancy: In-Service PVHO Acrylic Windows Guidelines, PVHO-2: 2003’ which provides technical criteria and guidelines for the in-service inspection, care, repair or replacement, testing and recertification of pressure vessels for human occupancy (PVHO) acrylic windows.”
 

The IMCA document comes to five specific conclusions:
 

  • Acrylic plastic viewports should be properly certified and marked prior to use.
  • It is generally agreed that they should be replaced after 10 years of service (PVHO-2: 2003 provides additional guidance when determining the length of service.
  • Examination of an acrylic plastic viewport by polarised light after the viewport has been in service is of very limited use, as all such viewports will show evidence of inbuilt stress.
  • The use of polarised light to check that acrylic plastic viewports are correctly mounted and evenly pre-stressed is not a simple matter and should not be used as a principal test
  • When mounting an acrylic plastic viewport, it is critical, especially when installing new ports in old pressure vessels, to check that the housing is the correct dimension and that the viewport and any sealing gaskets or O-rings are properly seated and of the correct size. A torque wrench should be used to correctly tension fixings diametrically to the manufacturer’s specification when replacing retainers.

 

IMCA’s new publication IMCA D 047 is available for free downloading from the IMCA website at www.imca-int.com with additional printed copies available to members at £2.50 and non-members at £5.00 (plus 20% for delivery outside Europe).
 

Maritime Reporter September 2014 Digital Edition
FREE Maritime Reporter Subscription
Latest Maritime News    rss feeds

People & Company News

VT Halter Begins Building LNG-powered ConRo Ships for Crowley

VT Halter Marine, Inc., a subsidiary of Vision Technologies Systems, Inc. (VT Systems), has commenced construction on the first of two liquefied natural gas (LNG)-powered,

NYK Line Joins PNW West Coast Metro Pool

Effective October 20, 2014, NYK Line has become a member of the PNW West Coast Metro Pool (WCMP) operated by Trac Intermodal. The WCMP operates chassis at all major marine terminals,

ISS Manages Heavy-lift Project at Port of Mombasa

Inchcape Shipping Services (ISS) announced it has completed another complex heavy-lift project in Africa, this time at the Port of Mombasa in Kenya. ISS was

Education/Training

Georgia Delegation visit Naval Academy "NYVaptsarov"

From 15 to 17oktomvri 2014. Naval Academy "N. Vaptzarov "hosted a delegation from Georgia led by prof. Sharabidze Irakli - Rector of the State Maritime Academy, city.

NMRA Awards Scholarship to Yacht Design Students

The National Marine Representatives Association (NMRA) awarded two scholarships to students pursuing careers in the field. Noah Luff of Ventura, California is one

Ocean Training Launches Blended Learning Course

Major revisions to the International Convention on Standards of Training, Certification and Watchkeeping for Seafarers (The STCW Convention) came into force in 2012.

Salvage

Boater Rescued from Sailboat Blaze

The U.S. Coast Guard assisted with the rescue of a boater Monday after the man's 33-foot sailboat caught fire five miles west of Windmill Point in the Chesapeake Bay.

WWII Wrecks Found 30 Miles off US Coast

The wreck of a World War Two German U-boat and a freighter that sank 72 years ago have been discovered off the North Carolina coast by U.S. researchers, officials said.

Sunken Barge Salvage Stops Traffic on Chicago River

The U.S. Coast Guard said it is restricting vessel traffic on the Chicago River to allow for salvage of a sunken barge. All cargo has been removed from the sunken

Marine Equipment

Virtual AIS Beacons Employed in MH370 Search

Vesper Marine, a manufacturer of marine safety products and virtual Aids to Navigation (ATON), announced that its Virtual AIS Beacons are employed in the search

ISS Manages Heavy-lift Project at Port of Mombasa

Inchcape Shipping Services (ISS) announced it has completed another complex heavy-lift project in Africa, this time at the Port of Mombasa in Kenya. ISS was

New Gate Transits the Panama Canal

The first gate for the new locks in the Pacific side began transit Wednesday morning through the Panama Canal, signaling another historic milestone in the progress of the Expansion Program.

 
 
Maritime Security Naval Architecture Navigation Pipelines Port Authority Ship Electronics Ship Repair Ship Simulators Shipbuilding / Vessel Construction Winch
rss | archive | history | articles | privacy | terms and conditions | contributors | top maritime news | about us | copyright | maritime magazines
maritime security news | shipbuilding news | maritime industry | shipping news | maritime reporting | workboats news | ship design | maritime business

Time taken: 0.1762 sec (6 req/sec)