Trafag’s ECTN 8477 pressure transmitter is certified for marine applications by DNV-GL with EU RO mutual recognition type approval. This certificate is recog-nized by all major classification societies: ABS, BV, CCS, CRS, IRS, KR, LR, ClassNK, PRS, RINA & RS.
The ECTN 8477, based on a ceramic sensor, is a very versatile pressure transmitter with measuring ranges from 0…100 mbar up to 0…250 bar, relative and absolute measurement and a range of corrosion resistant materials to choose from, including AISI316L, Duplex steel 1.4462 and titanium.
MRC stands for Mutual Recognition Certificate, often also referred to as MR TAC (Mutual Recognition Type Approval Certificate): One classification society evaluates the product and assesses the conformity with the respective specifications, and this organization also issues the MRC certificate.
The MR TAC is intended to enable Mutual Recognition (MR) of certain type approved products, through the uniform application of MR Technical Requirements, to enable those products to be installed on board of ships for which MR TACs are issued by one or more of the EU ROs
The EU ROs currently are:
Trafag ECTN 8477 is available in different materials to choose from, depending on the corrosiveness of the application. Wettted housing parts are available in steel grades AISI316L and Duplex steel 1.4462 as well as titanium.
Read our technical review to learn more about how to choose the right material for a salt water application.
Although in many cases regular stainless steel is used for cost reasons, experience in the field shows even the relatively common AISI316L can fail before time due to corrosion. Typically, the higher the temperature and / or the higher the salt or corrosive content, the faster it fails. There are two major criteria to assess the corrosion resistance against salt water of a stainless steel: both depending on the contents of the material.
Exact testing procedures to measure the PREN corrosion resistance of various types of stainless steel are specified in the ASTM G48 standard. Generally, the higher the PREN-value, the more corrosion resistant the steel is, and steels with PREN-values above 32 are considered seawater (corrosion) resistant. The PREN of 1.4404 (AISI316L) is 23…28.5 whereas the 1.4462 duplex steel is at 31…38, depending on the exact composition of contents. PREN Pitting Resistance Equivalent Number and CPT Critical Pitting Temperature
There are different methods to assess the CPT which is defined as the “lowest temperature on the surface of the specimen at which stable propagating pitting occurs under specified test conditions” (ISO 17864:2005), some basic empiric rules of thumbbased simply on the Molybdenum content. The CPT of 1.4404 (AISI316L) is between 24 and 27.5°C compared to 27.5…34.5°C of the 1.4462 duplex steel. Therefore, particularly for higher temperatures e.g. in tropical seawater, 1.4462 is the safer choice.
Practical assessment of corrosion resistance is typically performed with a salt mist test according IEC 60068-2-52:1996 which is also part of GL test specification. The samples are exposed during 2h to salt mist and then stored during 7days in warm humid environment. This procedure is repeated 4 times.
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