AMPP Pipeline Coatings key terms

A circuit formed when a metal surface has an anodic area, a cathodic area, an electrolyte connecting them, and a metallic path; current flows and metal dissolves at the anode.

Loss of coating adhesion spreading outward from a defect when cathodic protection generates alkaline conditions and hydrogen at the exposed metal, weakening the coating bond.

A coating whose main protective action is to slow the passage of water, oxygen, and dissolved ions from the environment to the steel surface, rather than relying on electrochemical inhibition.

The tendency of a coating film to allow water vapor, oxygen, or other small molecules to pass through it; lower permeability generally means better barrier protection for buried pipe.

The force holding a coating to the prepared steel or to the previous coating layer; it comes from mechanical interlocking in the surface profile and from chemical or polar bonding.

An electrical method that makes the pipeline the cathode of a corrosion cell, using sacrificial anodes or an impressed current system; the coating reduces the current needed.

A thermosetting powder coating applied electrostatically to heated pipe, where it melts, flows, and cures into a continuous film; widely used for buried and some offshore pipelines.

A pipeline coating system of fusion-bonded epoxy primer, a copolymer adhesive, and an outer polyethylene layer; the epoxy gives adhesion and the polyethylene gives mechanical and moisture protection.

A three-layer system similar to 3LPE but with a polypropylene outer layer, chosen for higher operating temperatures and better resistance to some mechanical and chemical exposures.

A hot-applied coating based on coal tar pitch with fillers, historically used on buried pipelines; it has good water resistance but is limited by temperature behavior and health concerns.

The temperature at which an amorphous polymer changes from a glassy, rigid state to a softer, rubbery one; for pipeline coatings it helps set the upper service temperature limit.

The coating applied at a girth weld after the pipe ends are joined, restoring corrosion protection and often matching or complementing the mainline coating's performance.

A field-joint product made of cross-linked polyolefin with a heat-activated adhesive; when heated it shrinks around the weld and bonds to the mainline coating to seal the joint.

An abrasive blast cleaning level in which mill scale, rust, and old coating are removed except for very light shadows or streaks; it is a common requirement for pipeline coatings.

The most thorough abrasive blast cleaning grade, leaving the steel surface uniformly bright with no visible mill scale, rust, or foreign matter; required for some high-performance coatings and certain specifications.

The roughness pattern created on steel by abrasive blasting; it provides mechanical keying for the coating and is measured in micrometers or mils from peak to trough.

Soluble salts such as chlorides and sulfates left on the steel after blasting or from marine exposure; they can pull water through a coating and cause blistering or disbondment if not removed.

A thin, brittle oxide layer formed on hot-rolled steel during manufacturing; it must usually be removed before coating because it can crack and detach, taking the coating with it.

The temperature at which air becomes saturated and water vapor begins to condense; coating work is normally stopped when the steel surface is close to this temperature.

A method of heating the steel pipe by passing it through an alternating magnetic field; it raises the substrate to the temperature needed for FBE application and cure.

A powder application method in which charged epoxy particles are sprayed onto a grounded, heated pipe; the particles adhere, melt, flow, and cure into a continuous film.

A plant process in which molten polymer is forced through a die around the coated pipe, forming the outer polyethylene or polypropylene layer of a three-layer system.

Rapid cooling of a freshly coated pipe with water or air to stop reaction, set the coating, and control crystallinity; it affects final adhesion and mechanical properties.

Spray equipment that meters and mixes two reactive coating components, such as epoxy resin and curing agent, at the nozzle just before application, giving a controlled cure.

The working time after two coating components are mixed during which the material remains usable; after this period it thickens or gels and must be discarded.

A small discontinuity or pinhole in a coating that exposes the steel or a lower layer; it is a starting point for corrosion and cathodic disbondment.

A test that passes a high voltage across the coating surface to find pinholes and thin spots; a spark or current flow indicates a holiday in the film.

A test in which a loading fixture is glued to the coating and pulled perpendicular to the surface until the coating detaches; the result and failure mode are recorded.

A laboratory test that creates an artificial defect, immerses the coated specimen in electrolyte, applies cathodic protection, and measures how far disbondment spreads from the defect.

A test where a weighted striker hits the coated pipe to assess whether the coating cracks, chips, or disbonds under mechanical impact; results help judge handling and installation damage resistance.

A test in which a coated specimen is bent around a mandrel or through a specified angle to check whether the coating stretches with the steel without cracking or losing adhesion.

A thermal analysis technique that measures heat flow into or out of a coating sample; for FBE it can indicate the degree of cure and glass transition temperature.

Localized lifting of a coating film into dome-shaped pockets, usually caused by water, solvent, or corrosion products trapped under the coating or by osmotic forces at soluble salt residues.

A series of international standards for coatings on buried and submerged pipeline transportation systems; it covers FBE, three-layer polyolefin, concrete, field joints, and related test methods.

Canadian standards for plant-applied and field-applied external pipeline coatings; they specify coating properties, application requirements, and test methods widely referenced in North American pipeline projects.

A standard published jointly by AMPP predecessor organizations NACE International and SSPC, often combining surface preparation and coating application requirements; example: SSPC-SP 10/NACE No. 2 for near-white blasting.

A document that gives hazard, handling, storage, and emergency information for a chemical product such as a coating or solvent; it must be available where the material is used.

An organic chemical that evaporates from a coating or solvent and can contribute to air pollution and worker exposure; regulations limit VOC content and require ventilation and respiratory protection.

A mineral present in sand and some blasting abrasives; breathing its dust can cause silicosis, so blasting operations require dust control, proper abrasives, and respiratory protection.

Management of used blasting grit, which may contain heavy metals, coatings, or salts; it must be tested, contained, and disposed of or recycled according to environmental regulations.