API RP 14E:2007 pdf download
API RP 14E:2007 pdf download.Recommended Practice for Design and lnstallation of Offshore Production Platform Piping Systems.
1.7 Corrosion Considerations.
a. General. Detailed corrosion control practices for platform piping systems are outside the scope of this recommended practice. Such practices should, in general, be developed by corrosion control specialists. Platform piping systems should, however, be designed to accommodate and to be compatible with the corrosion control practices described below. Suggestions for corrosion resistant materials and mitigation practices are given in the appropriate sections of this RP.
NOTE: The corrosivity of process streams may chance with time. The possibiitly of changing conditions should be considered at the design stage.
b. Weight Loss Corrosion. Carbon steel which is generally utilized for platform piping systems may corrode under some process conditions. Production process streams containing water, brine carbon dioxide (CO:), hydrogen sulfide (H2S, or oxygen (Os), or combinations of these, may be corrosive to metals used in system components. The type of attack (uniform metal loss, pitting, corrosion/erosion, etc.) as well as the specific corrosion rate may vary in the same system, and may vary with time. The coyrosivity of a process stream is a complex function of many variables includIng (1) hydrocarbon, water, salt, and corrosive gas content, (2) hydrocarbon wetabillty, (3) flow velocity, flow regime, and piping configuration, (4) temperature, pressure, and pH, and (5) solIds content (sand, mud, bacterial slime and microorganisms corrosion products, and scale). Coyrosivity predictions are very qualitative and may be unique for each system. Some corrosivity Information for corrosive gases found in production streams is shown In Table 1.1.
Table 1.1 is intended only as a general guide for corrosion mitigation considerations and not for specific corrosivity predictions. Corrosion inhibition is an effective mitigation procedure when corrosive conditions are predicted or anticipated (See Paragraph 2.1.b).
c. Sulfide Stress Cracking. Process streams containing water and hydrogen sulfide may cause sulfide stress crackint of susceptible materials. This phenomenon is affected by a complex interaction of parameters including metal chemical composition and hardness, heat treatment, and microstructure, as well as factors such as pH,hydrogen sulfide concentration, stress and temperature. Materials used to contain process streams containing hydrogen sulfide should be selected to accommodate these parameters.
d. Chloride Stress Cracking. Careful consideration should be giwn to the effect of stress and chlorides if alloy and stainless steels are selected to prevent corrosion by hydrogen sulfide and/or carbon dioxide. Process streams which contain water with chlorides may cause cracking in susceptible materials, especially if oxy1en is present and the temperature is over 140 F. High alloy and stainless steels, such as the AISI 300 series austenitic stainless steels, precipitation hardening stainless steels, and A.286” (ASTM A453, Grade 660), should not be used unless their suitability in the proposed environment has been adequately demonstrated. Consideration should also be given to the possibility that chlorides may be concentrated in localized areas in the system.
e. Application of NACE MRO1-75. MR-01-75 lists materials which exhibit resistance to sulfide stress cracking. Corrosion resistant alloys not listed in MR-01-75 may exhibit such resistance and may be used if it can be demonstrated that they are resistant in the proposed environment of use (or in an equivalent laboratory environment). Caution should be exercised in the use of materials listed in MR 01-75. The materials listed in the document may be resistant to sulfide stress corrosion environments, but may not be suitable for use in chloride stress cracking environments.
