BS 7361-1 PDF

Buy BS Cathodic Protection – Part 1: Code Of Practice For Land And Marine Applications from SAI Global. BS Part 1: -. BSI — British Standards Institution. BSI is the independent national body responsible for preparing British. Standards. It presents the. Find the most up-to-date version of BS at Engineering

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Ep is called the protection potential.

They are, however, frequently used in resistance to the soil by the installation of a single the form of a thin layer of 73661-1 or platinum anode of a size that can be conveniently handled.

The cathodic g Stray current. The sea-water is in direct contact with the metal electrode. Manganese is added to sequester iron impurities and make the anode potential more negative.

BS Cathodic protection. Code of practice for land and marine applications_图文_百度文库

High current densities coating on the carrier pipe within the sleeve as will therefore be necessary. Such These metals are used as the substrate because they an assembly is referred to as a groundbed.

The use of low driving potential anode 6. In such applications, the mechanical properties of the material and ability 7631-1 withstand abrasion by suspended matter may also be important.

When structures such as pipelines are being protected with impressed current, bd such as the availability of power supplies may, however, have an important bearing on the design. The cathodic protection of short lengths of immersed pipelines, for example river crossings, is dealt with in 4. Figure 5 — Anodic and cathodic reactions at a steel surface 10?

In aerated, near-neutral conditions, the iron ions produced at the anode react with the hydroxyl ions formed at a nearby cathodic site to produce ferrous hydroxide. However, structures in the atmosphere have been satisfactorily protected with a maximum spacing of mm between discrete anodes passing current.

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BS 7361-1:1991

This also facilitates renewal when ns effects see 9. Care should be taken in choosing the method for attaching cables to cast iron pipes because of the possibility of cracking and to lined pipes to avoid disbondment of the lining. The used if the soil resistivity is known with sufficient assessment bw risks due to lightning is 7361–1 with in accuracy.

It anode to the soil covers general principles, their application, the special problems arising in the protection of 1. The preferred practice is to carry number of anodes required to provide the calculated such liquids in tanks not fitted with anodes but ampere-year capacity can be calculated 3761-1 dividing where this is not possible, it is essential that any gas the total mass of anode material by the mass of the evolved has free access to the atmosphere and that individual anodes.

The current density required will depend on the amount of coating damage sustained during lowering and backfilling operations but, if care is taken, cathodic protection can be achieved initially with current densities of 0. It is essential that correct alignment of the flanges is achieved to prevent damage to the insulating sleeves.

BS – Cathodic protection. Code of practice for land and marine applications

Alternatively, electrodes such as graphite, whose electrochemical action is of an irreversible or non-reproducable nature, may be employed provided that they are regularly calibrated from a surface reference electrode. Calculation should take account of the current leaving the whole length of the rod and not be based on an assumption that it is concentrated through a hemisphere.

Where in near-neutral soil or water electrolytes and are sea-water was used in mixing, or unwashed sea dealt with in 5. The top of the foundation mound may be provided with a bitumen-sand carpet or some form of coating may be applied to the underside of the tank bottom.

In order to determine the maximum resistance that may be tolerated in the slip-ring circuit, the current flow may be estimated from the propeller area and the current density allowance recommended in 6. This can usually be carried out on commissioning of the cathodic protection system by measuring the potential difference across the isolating joint. This can be minimized by avoiding the use of very negative potentials and by using paints that are less susceptible to such damage see, for example, 6.

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For steel structures, the sacrificial anode systems see 9. Such anodes are available in the form of cast hollow cylinders with an internal metallic lining to which a cable is connected and sealed. The applied current remains interrupted and the off potential measurement is repeated.

By monitoring the readings from a surface electrode and an embedded electrode, gs differential can be calibrated for any particular part of the structure. A number of anodes can be supplied from a single control unit, even if they are mounted in different items of plant. However, bbs techniques are likely to be developed, and any technique which can be shown bd reduce IR errors to acceptable levels may be employed.

Steel in concrete, however, is in contact only with the relatively inert aggregates and hydrated Portland cement-gel forming the concrete, into which some chlorides may have become introduced. With a coated structure the resistance of the coating will also have an effect. This is principally due to increased turbulence near the propeller s and the formation of a cell between a bronze propeller and the steel hull.

These should be such that they will remain in good condition for a long time so that the potential at the rim corresponding to full cathodic protection at the tank centre can be determined.

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