Pipeline Free Span Corrections

PIPELINE FREE SPAN CORRECTIONS

OCS  owns and operates a full suite of  pipeline free span correction equipment. Pipeline free spans occur where bottom roughness on the seabed creates a situation where the pipeline spans between high points. Such spanning beyond certain prescribed limits creates over stressing during hydrotest or operations. Spans are corrected by placing grout bags underneath the pipeline and filling them with liquid cement or grout. Excessive Spans have to be corrected prior to pipeline pre-commissioning (flooding) so it is often advantageous to combine free span correction and pipeline pre-commissioning contracts.

OCS operates all the required equipment in-house and our technicians are multi-skilled enabling the customer to take advantage of the natural synergies and enhancing efficiency and cost effectiveness with a single contract award covering both services.

Principle Equipment involved with free span corrections:

• Cement Storage Silos.
• Air compressor to transfer cement to  mixer.
• Grout Mixer.
• Grout Pump.
• Hose Spooler with Chiksan.
• Grout bag deployment turntable equipped with a quick connect box.
• A frame or crane for deployment of turntable

OCS provides grout bags specifically configured for the pipeline diameter and span height.

The deployment vessel must be equipped with divers or an ROV to handle turntable operations or deploy the bag direct.  Grout is mixed in prescribed quantities on the surface and pumped into the bag while monitored by the ROV or divers.

The grouting distribution systems provide a delivery and recovery of HP grout hoses in water depths to 600m. This delivery system comprises of a hydraulically powered hose spooler incorporates a chiksan that allows grout to be pumped continuously while the hose are still on the reel.

OCS’s cement silos’ are in gauge 20ft standard ISO configuration They are easily transported by conventional shipping container lines and well suited to intermodal transportation. The Silos are provided with TIR, CSC certification.

OCS is equipped to handle the full range of free span correction activities utilizing grout bags to water depth up to 600m and span heights to 4.0 metres. For spans height in excess of 2.5  m in height  bespoke bags must be engineered and the bearing capacity of the seabed carefully assessed.

OCS is equipped to handle large projects or discrete project elements depending on the specific needs of the customer. During the preparation for free span correction or any offshore work, the safety of personnel, equipment and environment plays a vital role in the success of a project and as such, HAZID’s shall be conducted prior to any operations. These meetings are attended by key engineers and supervisors and all potential risks are identified and mitigation measures put in place to ensure they are as low as reasonably practicable.

OCS has undertaken eight (08) major free span correction projects for different customers;

Pipeline Free-span Correction: Pre-Qualification Document: Download