Nace Sp0170 Pdf 2021 (POPULAR – 2024)
Primary objectives:
[ Refinery Shutdown ] │ ┌───────────────┴───────────────┐ ▼ ▼ [ Dry Nitrogen Purging ] [ Alkaline Washing ] - Excludes O2 and H2O - Neutralizes acidic species - Keeps dewpoint < -45°C - Uses Soda Ash (Na2CO3) 1. Nitrogen Purging and Blanketing
NACE SP0170 focuses on a specific and dangerous form of corrosion: Polythionic Acid Stress Corrosion Cracking (PTA SCC).
: The 2021 context of this story involves sophisticated "shields." The standard outlines three primary defenses: Soda-Ash Wash : Neutralizing the acid before it can bite. nace sp0170 pdf 2021
When equipment must be opened for maintenance or catalyst dumping, nitrogen blanketing is impossible. Workers must wash the internal surfaces with an to neutralize any polythionic acid as it forms.
: Neutralizes any PTA that may form. The standard emphasizes that solutions must be properly applied to all surfaces and warns of potential effects on catalysts.
). When the unit is shut down and opened for a turnaround, moisture ( ) and oxygen ( Workers must wash the internal surfaces with an
This is the most common method specified in the standard. It involves thoroughly washing the affected equipment with a dilute alkaline solution, typically sodium carbonate. The alkaline solution neutralizes any polythionic acid that may have formed, rendering it harmless. The standard provides critical details on:
NACE SP0170 is a critical standard practice used in the petroleum refining industry to prevent Polythionic Acid Stress Corrosion Cracking (PTA SCC)
This polythionic acid is highly corrosive, specifically to the grain boundaries of susceptible alloys. typically sodium carbonate.
If you're looking for the 2021 version of this document in PDF format, here are some steps you can take:
) scales rather than sulfide scales. Consequently, their external surfaces present a significantly lower risk of PTA SCC. Core Mitigation Methods Mandated by NACE SP0170
), which can accidentally be triggered if the wash water contains trace chlorides.
