PNS Nitrogen Services Pipeline Pre-Commissioning and Decommissioning Services

PNS Nitrogen Services (PNS) provides pipeline pre-commissioning and decommissioning services for the oil and gas, and water industries.

PNS was founded at the end of 2006 in Emmen, the Netherlands. The PNS group consists of PNS Nitrogen Services, PNS Chemical Solutions and PNS Specialty Services.

Shutdown services including heater/furnace de-contamination and tube cleaning

Pre-commissioning and shutdown operations:

• Hydrostatic testing: various specifications for Gasunie, Fluxys, PD8010, B31.3 and TÜV
• Pneumatic testing: air/nitrogen up to 700barg
• Pipeline cleaning using polyurethane stud pigs, heavy-duty foam brush pigs, bi-directional brush pigs, mechanical scraper pigs, filtration of ethylene/propylene, mobile filter unit and flaring using combustion techniques
• Drying using super dry air, nitrogen and chemicals
• Inhibitor pigging using special pigs and inhibitors
• Pipeline inspections: portable data-logging tools, video inspection, gauging pigs, caliper survey pigs and DCVG surveys
• Rehabilitation: pipeline freezing and ‘intra-coat’ internal epoxy coating of pipelines

Pre-cooling of LNG unloading systems

Prior to the unloading of LNG into a newly built terminal it may be a requirement to pre-cool the unloading system with cold nitrogen gas; this was the case recently at the Isle of Grain LNG facility. PNS were contacted by CB&I with a request to pre-cool 1,200m of 36in line and the same length of 14in line in order to check the movement of the pipework at cryogenic temperatures and to avoid a large delta T between the top and bottom of the pipes during cool-down.

The relevant calculations were performed and the requirement was to provide 170t of nitrogen over a 30h period at -150°C. Within three days of the initial enquiry the equipment was on site ready to start and the nitrogen deliveries planned. The operation ran smoothly from start to finish and within 36h of commencing the client had begun to introduce LNG into the new plant.

This operation was testament to the experience that PNS has within the LNG industry and showed how quickly the company can respond to its clients’ needs.

On-line pipeline chemical cleaning

PNS provides on-line pipeline chemical cleaning using reactive chemistry and separators. These services include:

• On-line cleaning to remove black powder
• Wax / paraffin / asphaltene removal
• De-oiling
• De-rusting
• Inhibitor pig runs

Black powder and paraffin-removal chemicals

Deposits provide an environment to promote under-deposit corrosion, leading to catastrophic line failures. They reduce cross-sectional area of line, increase roughness, and greatly reduce efficiency, resulting in higher cost of compression (lower energy efficiency).

Advanced chemicals are very effective at removing black powder and paraffin. Black powder is recognized by the gas pipeline industry as the leading cause for loss of line efficiency and reduced quality of analysis of in-line inspection tools.