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MTS HgSSB AHX Inspection and Risk Analysis

Mercury in Aluminium Heat Exchangers

Mercury Technology Services (MTS) and Hg Solutions Sdn Bhd (HgSSB) provide consultation and guidance for all aspects of aluminum heat exchanger performance in situations where contamination by mercury has occurred or is possible. Services include process design analysis to predict mercury deposition, equipment inspection to locate mercury deposits and assessment of risk to operations based on the plant circum- stances. The risk analysis evaluates the equipment condition relative to industry experience and failure statistics and recommends methods to minimize risk exposure.

Mercury in Aluminum Equipment

When mercury condenses in aluminum equipment, bad consequences can result. Liquid mercury can cause cracking of welds, referred to as liquid metal embrittlement (LME), or amalgam corrosion when moisture is present. Brazed plate fin aluminum heat exchangers (AHX) that are used for gas separations in chemical processes are especially prone to mer- cury attack if precautions are not implemented to prevent mercury deposition. If equipment becomes contaminated by mercury, risk to operation exists. MTS specializes in AHX mercury risk assessment, evaluation of fitness for service and in formulating solutions.

Computational Modeling

MTS uses proprietary computational tools to predict deposition of mercury in cryogenic equipment. The amount and location of mercury in equipment is predicted based on inlet mercury concentration, process thermodynamics and fluid flow dynamics. Mercury in gas concentration limits, above which mercury condensation or precipitation might occur, are determined and reported.

Analytical Services

A very low level of detection of mercury in gas is necessary for computational modeling of mercury depo- sition in equipment. HgSSB offers analytical measurement services for mercury in gas and process streams to allow prediction of mercury deposition in equipment. The HgSSB laboratory offers state-of-the- art analytical methods, sampling procedures and detection instruments.


Based on the prediction of the computational modeling, a detailed inspection plan is constructed that details procedures to locate and quantify mercury deposition. The inspection plan is executed by HgSSB/ MTS as a turn-key project activity, usually in conjunction with a scheduled plant turn-around. The inspection is based on radiographic and visual techniques as well as indirect measurements. The inspection plan offers procedures for measuring mercury in warm-up gas and purge gas and details procedures for monitoring mercury in air when equipment blinds are installed or opened. Radiographs and borescope video records are interpreted based on over 20 years of experience with cold box assessment. Risk Analysis

HgSSB/MTS offer a comprehensive analysis of risk associated with operation of the aluminum equipment, which takes into account any contamination by mercury found in the inspection or estimated from computational modeling. The risk analysis draws upon industry experience concerning the engineering implications of mercury contamination in aluminum heat exchangers and provides advice on fitness for service, failure avoidance, risk minimization and related topics. In addition, the following technical issues are addressed:

  • Interpretation of inspection data relative to risk of mercury attack.
  • Calculation of fitness for service and operational risk.
  • Examination of metallurgical details and corresponding detrimental interactions between mercury and aluminum.
  • Comparison to common AHX mercury-induced failure modes and locations.
  • Provision of industry experience and failure statistics.
  • Assessment of oxide fatigue.
  • Correlation of mercury deposits with crack propagation distance (leak/rupture analysis).
  • Discussion of operational procedures to minimize risks of AHX failure including plant shutdown and startup procedures.
  • Mercury removal beds - process placement options, chemistry, prognosis for inspec performance.

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