DIG repairs
Excavation, Coating System and Pipeline Repairs
The Solution
- DTP has developed proven, structured methods for implementing an excavation and repair procedures for planning and conducting excavations and pipeline repair methods for damage and defects on your pipeline systems.
- DTP is committed to meet or exceed the Municipal, State or Federal requirements governing excavation and Qualification program under DOT, whichever is more stringent.
- DTP developed a quality check to ensure a safe working environment considering all relevant information pertaining to the excavation such as drawings, procedures, pre-jobs, local markers, JSAs, Work permit, qualifications, etc.
Activities
- Excavation (Dig) – Location and Verification of defects:
- Dents, Growth, Girth Weld, Hard spot, Corrosion, etc.
- Coating repairs:
- Coal Tar Enamel, Epoxy-Based Flow, Fusion Bonded Epoxy,
- Hydrophobic, Polyamide, Polyurethane Coating
- Temporary and permanent repairs:
- Sleeves Type A & B or Clamp, Composite and welded
CASE STUDY
- Client: TC Energy
- Date: 22/06/2023
- Pipeline: Tamazunchale pipeline system, NPS 36
- Location: The three sites were repaired at Naranjos – Tamazunchale (TMZ) pipeline system
- Scope: Excavation of investigation
1. Problem statement
According to the cathodic protection study (CIS/DCVG) carried out by TC Energy, areas were detected for potential FBE coating disbonding and/or mechanical damage in the pipeline. It was necesary to carry out verification excavations to inspect, evaluate pipeline and coating conditions and repair the coating system as needed.
2. Solution
Uncover the entire pipeline segment to perform a 360° inspection (VT & NDEs) to assess the coating/pipeline condition and determine the best repair option such as perform a surface preparation through abrasive blast media (blackbeauty) to a minimum cleanliness and coated immediately. The coating materials were applied, tested and holiday inspected. Rockshield protection was placed as additional protection layer as required.
3. Procedure
EXCAVATION
- Site access road was improved for vehicle, material and machinery transportation.
- Site grading included vegetation cleaning, removal and disposal of topsoil.
- Delimitation of the entire área designated for the remediation.
- Topographic survey and location of line pipe, width of 30 m (15 m on each side of the axis) and a length of 60 m (20 m downstream of the pipe axis and 30 m upstream) to define elevations.
- Gas monitoring and line pipe detection in a regular basis.
- Excavation of a trench 3.5 m wide and of variable depth along four sections of up to 10 m in length and a total length of up to 35 m, in such a way that the pipeline is uncovered in its entire length of the section, placing supports every 8 m with pipe pillow.
- Manual excavation was carried out at the Compressor Station (CS).
- The line pipe had to be free (uncovered) in a section of 10 meters with 1.50 m on both sides of the pipe.
Repair and coating
- Once the entire pipeline is uncovered, a 360º visual inspection of the coating must be carried out by TC Energy Integrity Field Services.
- Testing areas subject to abrasive cleaning and coating repair are determined by TC Integrity Field Services.
- Definition and preparation of areas to be repaired.
- Abrasive / mechanical cleaning with Black Beauty
- Recoating of the pipe in accordance with TC Energy’s procedure “TES-CO-EPU-GL Field-Applied External Liquid Coatings for Steel Pipeline Systems (CAN-US-MEX)” and supervision of TC Energy.
- The following measurements are carried out during this stage:
- Chloride detection test in areas to be coated
- Measurement of environmental conditions (HR, Dew Point, TS, TA, Wind speed.
- Blotter test.
Coating must be applied by NACE specialists.
- All equipment must be certified.
- Curing, adhesion and dry film thickness tests are carried out.
- Application of Rock Shield as additional protection layer.
Filling and Cover
- Once the repair is completed, the soil compaction of all áreas associated to this remediation were performned in accordance with contractual specification and geotechnical report.
- The filling of the excavation will be carried out following the TC Energía procedure, warning tape was install as additional safeguard to the pipeline system.
- Revegetation of the impacted area was done with a local species and the access road was left in as good or better condition after construction was completed.
