METHOD STATEMENT FOR UNDERGROUND HDPE PIPING INSTALLATION

CONTENT:

1.       GENERAL INFORMATION

1. Introduction
   1. Purpose
   1. Scope of Work
   1. Location
   1. Definitions

2.       EXECUTION

• Materials
  • Tools & Equipments
  • Procedure of Work
  • Responsibilities

3.       QA / QC

• Reference Standard
  • Responsibilities
  • Test and Measurement
  • Inspection

4.       SAFETY

• Guidelines
  • Responsibilities
  • Hazard Analysis

5.       ATTACHMENTS

1. GENERAL INFORMATION

     1.1    Introduction

TECNIMONT Arabia Ltd. (TAL) has awarded KETTANEH Construction Saudi    Arabia Ltd. the subcontract for the construction of PC3 Plant of Rabigh Development Project, Rabigh K.S.A.

1. Purpose

To provide a procedure to be perform throughout the project to ensure conformity with project specifications and approved drawings.

1. Scope of Work

This method statement outlined the procedure of the installation of underground HDPE piping for Sanitary Sewers and Industrial Drainage System in the Rabigh Development Project – PC3 in accordance with project specifications and approved drawings.

1. Location

The HDPE pipes shall be used for underground piping, above ground piping and within the building plumbing system as specified in the approved drawings for the HDPE & Butene Area of PC3 Plant – Rabigh Development Project, Rabigh K.S.A.

1. Definitions

SAES        :         Saudi Aramco Engineering Standard

PIP            :         Process Industry Practices

HDPE        :         High Density Polyethylene

QA / QC    :         Quality Assurance / Quality Control

•      EXECUTION

     2.1   Materials

1. HDPE Pipes & Fittings

• Tools and Equipments

1. Portable Electro-fusion Welding Unit
2. Hand Saw
3. Grinders & Drill machines
4. Various Hand Tools
5. Excavator & Loaders
6. Dump Trucks, Trailers and Water Trucks
7. Compactors

• Procedure of Work

• Pipe Installers

• Installation of HDPE piping shall be done by trained personnel in the proper handling and usage of applicable tools and equipments prior to start of installation.
• HDPE pipe installer shall assemble a trial joint with the same type of materials and techniques to be used in the actual installation.
• The trial joint (test joint) shall be tested to at least 3 meters water head for a minimum of 2 hours.

• Handling and Storage

• All pipes and fittings shall be inspected upon receipt at job site. If any defect or damage is found, it shall be segregated and will be subject for replacement.
• Loading and Unloading of pipes shall be properly controlled by using guide ropes and proper lifting procedures. Straps, slings and ropes shall be used. Manual loading & unloading can also be done for small pipes.
• HDPE pipes and fittings shall be stored out of direct sunlight in a building or under a cover that allows free air circulation.
• Racks shall conform to factory shipping packages for each pipe size. Shelves shall be provided for continuous support of the pipe.
• If pipe is stored on racks or bearing boards, the supports shall be at least 75 mm wide. Supports shall be spaced at 3 meters center maximum with the first support 1.5 meters from the end of the pipe.
• Adequate side support shall be provided to prevent slipping or rolling.
• HDPE Pipes and fittings shall not be stored direct from the ground.
• All supporting surfaces shall be free from sharp objects.
• Pipes and fittings shall be properly protected from impact especially on their ends.

• Assembly, Joining & Laying

• Before assembly, each pipes and fittings shall be examined from damages.
• Pipe inside surfaces shall be cleaned by rags or by purging air from an air compressor before assembly.
• HDPE piping shall be socket fusion welded in accordance with the manufacturer’s instruction (see attachments) in conjunction with the project specification.
• HDPE piping shall be cut square using pipe cutter or fine toothed hand saw.
• Chamfer or deburr pipe using files or sand papers before jointing.
• HDPE pipes and fittings mating surfaces shall be clean and dry before welding.
• For Underground Piping:
• 250 mm nominal pipe size and less may be assembled next to or in the trench.
• Piping larger than 250 mm nominal pipe size shall be assembled in the trench.
• Crane and (or) labors shall be used for placing pipes into the trench using proper tools and equipments such as ropes, straps and slings to control and maintain proper handling procedure.
• Before start of the pipe laying, the bottom of the trench shall be dry, continuous, smooth, free of rocks and to the line and grade shown on the installation drawings.
• The clean sand bedding shall be compacted according to SAES-S-070.
• Pipe location, elevation and slope shall be maintained by a surveyor. A survey report shall be made after final installation.
• Sand bags shall be placed at the bottom of pipes to meet the exact elevation and slope of the pipe being installed. The sand bed shall be then adjusted accordingly to maintain the pipe on the ground is on a firm bed for its entire length.
• Excavation a little deeper on the place where the pipe is to be joined shall be done to allow access for the installer for proper joining method.
• Pipe shall be installed continuously downhill without low points and high points.
• Pipe is to be anchored by partial sand covering of the pipe to prevent floatation and to maintain its alignment and level.
• At the end of every work shift, personnel performing the pipe installation shall ensure that the pipe ends are capped to prevent entry of foreign materials.
• For Above Ground Piping:
• All piping shall be supported in such a manner to maintain its alignment and prevent from sagging.
• Suspended piping shall be supported with metallic hangers of sufficient strength at maximum 3 meters interval.
• Plumber’s strap, pipe clamps and brackets shall be used for suspended piping.

• Trenching and Bedding

• Prior to start of excavation, make sure that the pipe line coordinates and elevation has been checked and verified by the surveyor.
• Excavation and sand bedding shall be done mainly by equipments (excavators and loaders).
• Manual excavation is required in cases where equipments are not possible or are not allowed due to safety reasons or where manual excavation is more convenient in a specific area.
• Excavated materials shall be placed at a suitable distance from the edge of excavation so that materials do not fall back into the trench or excavated materials will be put directly to a dump truck and will be unloaded to a designated area away from the trench.
• Loaders shall be used for placing sand bedding materials into the trench while labors will spread manually to meet the correct elevation and slope throughout the trench.
• The minimum trench width from the bottom to 300 mm above the top of the pipe shall be 300 mm for pipe size 90 mm & below and 300 mm + Outside Diameter for pipe size 100 mm & above.
• Depth of trench shall be dug deep enough to provide a ground bed of at least 150 mm from the bottom of the pipe.
• Clean sand bedding layer of 150 mm thickness shall be compacted to at least 70% relative density or 95% Proctor density.
• The trench bottom shall be continuous, smooth, free of rocks and to the line and grade shown on the approved installation drawings.
• If trench de-watering is necessary, no pipe installation shall start until the design of the de-watering system has been approved.
• Trench de-watering system shall be done in accordance with SAES-S-114.
• De-watering system shall be done by trained personnel only.

• Backfilling

• Make sure that Inspection & Testing has been done and approved before any backfilling works starts.
• Backfilling shall be done mainly by equipments (loaders & compactors) while some labors spreading manually the sand and backfill materials wherever required.
• The pipe shall be covered to at least 300 mm clean sand above the top of the pipe and shall be compacted by water flooding and hand tamping only.
• Backfill above 300 mm sand cover shall be on site excavation or borrowed materials.
• Backfill above sand cover shall be compacted according to ‘SAES-S-070 Table-5 Minimum Compaction’.
• Minimum cover on top of pipe shall be in accordance with ‘SAES-S-070 Table-2’.
• If it is impossible to achieve the minimum cover as specified, the piping shall be protected by concrete slab or metallic casing in accordance with SAES-L-460.

• Gravity Test

• Gravity sanitary sewer and Industrial drainage system shall be tested with potable water, well water or sea water.
• Gravity test shall be done from manhole to manhole or a column of water equivalent to the rim elevation of the upstream manhole if pipe is to be tested separately.
• Gravity test shall be maintained for a period of 4 hours for lines whose joints have not been backfilled or are above ground piping while 24 hours shall be maintained for lines whose joints have been backfilled.
• If manholes are not part of the test or a section of pipe is to be tested, the pipe ends shall be covered with plumber’s test plugs.
• An extension pipe is provided on the test plugs at selected location for water filling and drain points and at least one pipe riser for the water head required that shall be accessible for visual inspection.
• Plumber’s test plugs that are not used for other purposes shall be kept open while filling of water to release air inside the system and shall be closed when the system has been properly vented.
• Water filling into the pipe being tested shall be from a water truck or a ground level water tank with electric or engine-driven pump. A water hose shall be placed direct to the manhole, to the pipe being tested or to a pipe connection provided at the plumber’s test plug.
• All joints shall be exposed and cleaned for visual inspection.
• Partial sand covering and backfilling on the body of the pipe being tested shall be done to prevent floatation during test.
• Drain valve shall be provided at the lowest portion of the pipe being tested for safe draining after inspection.
• Water used for testing can be re-used for another gravity test, for water flooding of pipe sand covering, for water spray of trenches or discharge to a designated area.
• Repair methods for leaking pipes, joints and fittings shall be in accordance with SAES-S-070.
  •     Responsibilities

• Site Engineer shall organize, manage and supervise all activities related to the installation of HDPE piping with regards to safety, quality and productivity of the over-all performance of the work.
  • Site Supervisor and Foreman shall arrange all the necessary manpower, tools and equipments and implement the approved working procedure for a proper execution of the work with regards to safety, quality and productivity.
  • Surveyor shall provide all necessary coordinates and elevation at the start of excavation up to final installation of pipes.

3.0     QA / QC

     3.1   Reference Standards

• SAES-S-010      –         Sanitary Sewers
• SAES-S-020      –         Industrial Drainage and Sewers
• SAES-S-060      –         Saudi Aramco Plumbing Code
• SAES-S070        –         Installation of Utility Piping system
• SAES-L-610       –         Non-Metallic Piping System
• SAES-L-460       –         Pipeline Crossings Under Roads and Railways
• SAES-A-114      –         Excavation and Backfill
• PIP CVS02700   –         Underground Sanitary Sewer Specification
• PIP CV102720   –         Sewer Details
• PIP CVS02100   –         Site Preparation, Excavation and Backfill
• Material Submittal MS-C-027 Rev. 0
• Material Submittal MS-C-037 Rev. 0
• Kettaneh QA / QC Plan

     3.2   Responsibilities

•    QA / QC Inspector shall make sure that all activities related to the piping installation are carried out in accordance with the project specification and approved drawings. He shall arrange Inspection & Testing required with TECNIMONT and PETRO Rabigh in accordance with the QA/QC Plan. He shall maintain and keep records for all QC Documents.
•    Site Engineer, Supervisor and Foreman shall assist the QA/QC Inspector whatever he required in relation to the quality of works, procedures or documents.

     3.3   Test and Measurement

•    No special device or equipment to be used for the gravity test of underground HDPE piping.
•    By simply marking the water level at the manhole or pipe being tested at the start of the test, the piping being tested shall be considered satisfactory if no reasonable drop on the water level after the specified test period and if no evidence of water leakage on the body of the pipes, fittings and to the joints.

     3.4   Inspection

• Request for Inspection shall be issued to TECNIMONT / PETRO Rabigh Project Inspection 24 hours in advance on weekdays and 48 hours in advance for weekends and holidays.
• Inspection shall be done in accordance with the QA / QC Plan.
• During Inspection, all exposed pipes, joints and fittings shall be carefully examined for leakage.
• The piping being tested shall be satisfactory if there is no evidence of leakage or reasonable drop in the water head after the specified test period.
• Leaking pipes, joints and fittings shall be replaced and test shall be repeated until the system is proven satisfactory.

4.0        SAFETY

•   Guidelines

• Person working with HDPE piping shall wear the Personal Protective Equipments at all times on the job site.
• All trenches shall be provided with proper barricades such as physical barriers and safety tapes.
• Warning sign boards and lights shall also be provided where necessary.
• Proper access such as ladders and ramps shall be provided at designated areas where workers can go in and out the excavated area.
• Spotter shall be present at the job site whenever excavators and loaders are working.
• Rigger shall be present at the job site whenever pipe is to be lifted by crane.
• Spotter and Rigger shall wear reflective high visibility vest.
• Excavation Permit shall be provided before start of any excavation.
• All equipments shall have Aramco stickers or safety tags to ensure that said equipments are approved for a safe working condition.

     4.2   Responsibilities

• Safety Inspector / Officer in conjunction with the site supervisor or foreman shall physically check and conform that all safety requirements had been provided and implemented.
• Operators, riggers and spotters of heavy equipments shall follow and implement proper safe working procedure at all times.

     4.3   Hazard Analysis

5.  ATTACHMENTS HDPE Jointing Method by Electrofusion Welding