External concrete weight coating application is performed by “impingement” method. Concrete coating is applied by continuously throwing the concrete mix on longitudinally moving and rotating pipe with protective coating and installed steel reinforcing cage and/or with the use of reinforcing wire mesh. Application of concrete weight coating allows to avoid coming of pipes to the surface and provides protection from mechanical damages. Concrete is applied on factory insulating coating. Concrete application may be performed using concrete of different densities, which makes it possible for the product to comply with different project requirements. Coating thickness can vary from 20 mm to 150 mm. Concrete application provides pipe coating of uniform thickness with minimum deviations of specified weight.
Concrete weight coating is applied to the exterior of steel pipe to provide negative buoyancy or mechanical protection for submarine pipelines. Ideal for pipe ranging from 4 to 48 inched OD or greater. It can be applied over most pipe coatings. The concrete formulation can be tailored to any specified density specification. Typical product formulations are 140, 165 and 190 pounds-per-cubic-foot (nominal), but, greater densities are also available. Thicknesses can be applied from one to eight inches. Concrete compressive strengths range from 3000 psi and greater; reinforcing galvanized wire is available in several mesh and gauge values, with single or multiple feeds. Embedded depth controlled for additional strength and stability.
Application: CWC, currently the most important counter weight product in offshore pipeline , consists of cement, water, aggregates and reinforcement materials, with its characteristics such as fixing the pipeline stably on the seabed and offering effective mechanical protection for the pipeline . Compared with the pipe-in-pipe insulation, CWC is more efficient in saving steel, reducing labor force in the course of pipeline installation and lowering the operational cost.
Accurately proportioned quantities of cement, iron ore, sand and/or granite aggregate are mixed together to yield the specified density. Controlled wire placement during concrete buildup achieves the specified wire depth within the coating. Weighing verifies that each joint meets project-specific gravity requirements. Concrete ends are cleaned and excess wire is trimmed. After curing, joints are stockpiled and ready for loadout.
CONCRETE WEIGHTED COATING REFERNCE SPECIFICATION
ISO 21809-5:2009, Petroleum and natural gas industries -External coatings for buried or submerged pipelines used in pipeline transportation systems - Part 5:External concrete coating.
The standards covers all the current concrete-coating processes-side wrap( or compression wrap) process,concrete spraying (or impingenment), form (or pour) process and slip-forming process,all of them using primary steel reinforcement through a galvanized steel mesh or a rebar cage.It defines the requirements for the pipe cutback area,steel reinforcement positioning,anode installation and acceptable cutback methods.
AS 1303 Steel Reinforcing Wire for Concrete
AS 3972 Portland and Blended Cements
API 5L1 Recommended Practice for Railroad Transportation of Linepipe
API RP 5LW Recommended Practice for Transportation of Linepipe on Barges and Marine Vessels
ASTM A82 Steel Wire, Plain for Concrete Reinforcement
ASTM A185 Standard Specification for Steel Welded Wire Fabric, Plain, for Concrete Reinforcement
ASTM A615M Standard Specification for Deformed and Plain Billet-Steel Bars for Concrete Reinforcement
ASTM C33 Standard Specification for Concrete Aggregates
ASTM C39 Standard Test Method for Compressive Strength of Cylindrical Concrete Specimens
ASTM C42 Standard Test Method for Obtaining and Testing Drilled Cores and Sawed Beams of Concrete
ASTM C87 Standard Test Method for Effect of Organic Impurities in Fine Aggregates on Strength of Mortar
ASTM C125 Standard Terminology Relating to Concrete and Concrete Aggregates
ASTM C136 Standard Test Method for Sieve Analysis of Fine and Coarse Aggregates
ASTM C227 Standard Test Method for Potential Alkali Reactivity of Cement Aggregate Combinations
ASTM C294 Standard Descriptive Nomenclature for Constituents of Concrete Aggregate
ASTM C295 Standard Guide for Petrographic Examination of Aggregates for Concrete
ASTM C309 Standard Specification for Liquid Membrane-Forming Compounds for Curing Concrete
ASTM C642 Standard Test Method for Density, Absorption and Voids in Hardened Concrete
BS 1881 Methods of Testing Concrete
BS 3148 Methods of Test for Water for Making Concrete (including notes on the suitability of the water)
BS 4482 Hard Drawn Mild Steel Wire for the Reinforcement of Concrete
BS 4483 Specification for Steel Fabric for the Reinforcement of Concrete
BS 4449 Specification for Carbon Steel Bars for Reinforcement of Concrete
ISO 4012 Concrete. Determination of Compressive Strength of Test Specimen.
OFFSHORE LINE PIPE REFERENCE SPECIFICATION
API 5L PSL1/PSL 2/PSL3 Line Pipe: Gr. B X42, X46, X52, X56, X60, X65, X70, X80/BM.X42M,X46M,X52M,X60M,X65M,X70,X80M
ISO 3183-1/2/3 Petroleum and Natural Gas Industries-Steel Pipe for Pipelines-L240M,L290M,L320M,L360M,L390M,L415M,L450M,L485M,L555M,L690M
ISO 3183-3 Petroleum and Natural Gas Industries Steel Pipe for Pipelines-L245NC / L245NCS,L290NC / L290NCS, L360NC / L360NCS, L290MC / L290MCS, L360MC / L360MCS, L415MC / L415MCS, L450MC / L450MCS, L485MC / L485MCS, L555MC
DNV OS-F101 Submarine Pipeline Systems-SAWL 245,SAWL290,SAWL 320,SAWL 360,SAWL 415,SAWL 450,SAWL 485,SAWL 555
NACE MR 0175/ISO 15156-2 Petroleum and Natural Gas Industries – Materials for Use in H2S Containing Environments in Oil and Gas Production. Part 2. Cracking resistant Carbon and Low Alloy Steels, and the Use of Cast Irons.
NACE TM 0177 Laboratory Testing of Metals for Resistance to Sulfide Stress Cracking in Hydrogen Sulfide (H2S) Environments
NACE TM 0284 Standard Test Method - Evaluation of Pipeline and Pressure Vessel Steels for Resistance to Hydrogen-Induced Cracking
DEP 126.96.36.199-Gen Linepipe for critical service (amendments/supplements to ISO 3183-3)
API 5L: TUBOS PARA CONDUÇÃO DE PRODUTOS PETROLÍFERO
BS 7191 All Specification for Weldable Structure Steels for Fixed Offshore Structures
The mechanical tests provided include
Tensile testing - up to 100kN
Hardness testing - Vickers, Rockwell, Brinell & Leeb (portable)
Charpy impact testing - down to -128° C
Tensile Testing to: AS 1391, AS 2205.2, AS 1855, ASTM E8, ASTM A370, ISO 6892, ASME IX QW 150, EN 895, API 5L, AS 1397, AS 3678, AS 3679.1, AS 3992, AS 1163, AS 2885.2, AS 1554 Series, AWS series, ISO 15614 series, IS0 9956, ISO 9606 series, ISO 5817 series and other Australian and International standards.
Hardness Testing to: AS 1815, ISO 6508.1, ASTM E18, ASTM A370, ISO 6506, AS 1816, ASTM E10, ISO 6507, AS 1817, ASTM E92, ASTM E384, ASTM A956, ASTM E110, AS 1982 and other Australian and International standards.
Charpy Impact Tests to -128C: AS 2205.7, ASTM E23, ASTM A370, ASME IX, AS 2885.2, AS 1554 series, AS 3992, AS 3678, AS 3679.1, AS 3679.2, AS 1163, ISO 15614 series, DIN EN 875, DIN EN 10045.1, AWS series, ISO 9956, ISO 9606 series and other Australian and International standards.
Fracture Tests (Nick & Fillet Breaks) to: AS 2205.4.1, AS 2205.4.2, ISO 9017, ASME IX, AS 1665 and AS 2885.2 and other Australian and International standards.
Macro Tests: AS 3992, AS 4037, AS 2885.2 Tier 2, AS 1554.1 to .6, ASME IX, AWS D1.1 to .6, ISO 15614.1 to .8 & ISO 15614.11 to .13, ISO 9606.1 to .5, EN 287.1 to .4, EN 288.1 to .4, API 650 and other Australian and International standards.
||1800-3050 kg/m3 (112-190 lbs/ft3)
|Characteristic proctor cylinder compressive strength (28 days)
||30-40 MPa (4350-5800 psi)
|Characteristic cube compressive strength (28 days)
||40-50 MPa (5800-7250 psi)
|Minimum concrete thickness
||25 mm (1”)
|Maximum concrete thickness
||150 mm (6”)
|Maximum pipe diameter
||1220 mm (48”)
|Minimum pipe length
||5.5 m (18’)
|Maximum pipe length
||19.8 m (65”)