H-321 – Pipeline Cleaning & Drying Plan
Revisions Date Description Author 9/22/15 Issued Zachary Fuller 5/4/16 Added DeFasko PosiTector DPM Dewpoint Meter as an Sheila Miller alternative to the Control Company model Note: When using this plan, care should be taken to safely launch and receive all pigs. Refer to EQT Midstream Design & Construction Manual, Section 10.2 Pipeline Construction Standard for additional information.
Phase 1 – Proving / Initial Pipeline Cleaning
Following pipeline construction, internally clean the pipeline to remove construction debris and surface corrosion. The first pig run shall be a proving run with a RCC-DD pig to ensure the pipeline is free from any obstructing objects. After a successful pass with no damage, cleaning will begin by running SCC-WB wire brush pigs until the pipeline is clear of heavy debris and scale.
12” – Girard RCC-DD-12 Red Criss-Cross Squeegee, Double Dish Pig 12” – Girard SCC-WB-12 Scarlett Criss-Cross Wire Brush Pig
Phase 2 – Filling / Hydrostatic Test
Following initial pipeline cleaning, the pipeline is ready for hydrostatic testing. Fill the pipeline at a constant rate until all air is removed and the pipeline is full of water. Use two (2) RCC-DD pigs in front of the fill water to help prevent air bubbles.
12” – Girard RCC-DD-12 Red Criss-Cross Squeegee, Double Dish Pig
The pipeline shall then be tested per EQT Midstream Design and Construction Manual, Section 9.1 Strength Testing of Pipeline Facilities. At the end of the test, the Contractor shall lower the pressure slowly by venting the water.
Phase 3 – Dewater Pipeline
After a successful hydrostatic test, steps can be taken to dewater the pipeline. All block valves shall be fully open for dewatering. To dewater the pipeline, push the two (2) - RCC-DD pigs (from the previous phase) back to the fill point with compressed air. Keep back pressure on the discharge end to hold the slug of water together. Run the RCC- DD pigs back and forth as needed to dewater the pipeline.
12” – Girard RCC-DD-12 Red Criss-Cross Squeegee, Double Dish Pig
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Phase 4 – Initial Pipeline Drying
After the pipe has been dewatered, run one (1) RCC-DD and two (2) YBS pigs together using compressed or dry air. Continue drying with this method until no free water is received with the pigs.
12” – Girard RCC-DD-12 Red Criss-Cross Squeegee, Double Dish Pig 12” – Girard YBS-12 Yellow Bare Swab Drying Pig
Phase 5 – Final Pipeline Cleaning
Once the free water is removed from the pipeline, brush pigs should be utilized to remove mill scale, rust and debris from the inside of the pipe. Run a minimum of three (3) - SCC-WB or GZB pigs (or equivalent, as approved by EQT). Each brush pig shall be run separately, and not as a group. Wire brush pigs shall be run until the pipeline is clean and free of debris and scale.
12” – Girard SCC-WB-12 Scarlett Criss-Cross Wire Brush Pig OR 12” – Girard GZB-12 “Z” Brush Pig with Polyurethane Scraper Cups
Phase 6 – Final Drying
After the pipeline is clean, run YBS pigs until the liquid penetrates the foam less than ¼ inch.
12” – Girard YBS-12 Yellow Bare Swab Drying Pig
Once the penetration depth is verified by an EQT representative, continue drying with dry/heated air or nitrogen as necessary.
The mainline block valves will remain inoperable and in the open position. The valve body cavities and bypass piping shall be dried using dry/heated air or nitrogen. With the pipeline pressurized to 10 psig minimum, the drain valves shall be opened and the mainline valves cycled. A dew point reading shall be taken at each block valve body bleed to ensure the valve body has reached the proper dryness.
Pipeline drying should continue until a dew point of -40ºF (Transmission Quality) or less is reached. The dew point shall be verified by an EQT representative using a hygrometer as approved by Design Engineering and calibrated not more than a year prior to use: Currently approved:
Control Company Traceable Hygrometer Model 4085 DeFasko PosiTector DPM
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Once the specified dew point is reached, the pipeline is considered to be dry.
Phase 7 – Nitrogen Blanket
A nitrogen blanket between 5 psig and 50 psig should be put on any pipeline that is not planned to be in service within 4 weeks of completion.
Quantities
Item Minimum Description Recommended Qty
Girard RCC-DD-12 Red 1 Criss-Cross Squeegee, Double Dish Pig
Girard SCC-WB-12 1 Scarlett Criss-Cross Wire Brush Pig
Girard GZB-12 “Z” Brush 1 Pig with Polyurethane Scraper Cups
Girard YBS-12 Yellow Bare 20 Swab Drying Pig
Control Company (1) Traceable Hygrometer Model 4085
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DeFasko PosiTector DPM (1) Dewpoint meter
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