TOL corrosion is reported to occur in large diameter wet gas pipeline in stratified flow conditions
due to low fluid velocities1. With increasing distance from the inlet, the wet gas pipeline becomes
cooler as it loses heat to the environment. Such cooling causes water, hydrocarbon, and other
high vapor pressure species to condense on the pipe wall. The upper part of the pipe will
constantly be supplied with freshly condensed water while the less corrosive water saturated
with corrosion products will be drained along the pipe wall to the bottom of the line.
Product Number:
51322-17787-SG
Author:
Larry Chen, Nihal Obeyesekere, Jonathan Wylde, Michael Sim
Publication Date:
2022
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Bottom-of-Line (BOL) corrosion inhibitor design and production has been a successful story and
a mature technology in oil and gas industry. However, preventing Top-of-Line (TOL) corrosion
with inhibitors is very challenging, and even more challenging when pursuing dual functional
corrosion inhibitors that serve for both BOL and TOL at the same time. Designing a dual
functional corrosion inhibitor for both BOL and TOL is a difficult and challenging task, with several
hurdles to overcome in this endeavor. Some of the difficult issues are: calculate the treating
weight between the top of line and bottom of line, how to make the combined products perform
effectively for both top and bottom of lines, how to make the low and high volatile molecules for
mitigating BOL and TOL corrosion to be compatible and homogenous in a single blend.
More than 60 active components were used to develop more than 30 formulated products. These
products were screened using a TOL rig, RCE and RCA methods to pare down the products.
These were then subjected to various physical properties such as flash point, viscosity
requirements, emulsion and foaming tendencies as well as thermal stability issues. Finally, two
products were selected that satisfied all desired chemical characteristics and performance.
\One BOL and TOL combined product denoted as TB-3 was developed for treating both BOL
and TOL applications. TB-3 is a water-soluble product that exhibited excellent thermal stability up to 110oC and demonstrated high efficacy in corrosion inhibition for both BOL and TOL
applications under sweet or sour conditions with or without the presence of organic acids.