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INSPECT and Auto-Refrigeration

Minimum Safe Operating Temperature (MSOT) curves, also referred to as Minimum Pressurization Temperature (MPT) curves, are used to ensure that carbon steel equipment can safely operate when exposed to low temperature conditions. Common applications include the olefin and hydrocarbon processing industries where safety concerns created by auto-refrigeration may occur. MSOT curves are employed to determine which process conditions put equipment at risk of failure by brittle fracture. They are created by performing API 579 Part 3 assessments for all pressure-temperature conditions expected in service. Because of the number of calculations required, this has historically been an expensive, time consuming task. INSPECT automates this RAGAGEP procedure and shows how process conditions interact with the equipment’s Minimum Allowable Temperature (MAT).

INSPECT’s MSOT Curve Benefits

  • MDMT (minimum design metal temperature) data may not be  available for old or undocumented vessels. Creating a MSOT curve with INSPECT solves this problem quickly.

  • INSPECT’s MSOT curves are plotted against process Vapor Pressure Curves.  This information can then be used for creating integrity operating windows (IOW’s).

  • Reduces time and expense when creating MSOT’s manually or through outsourcing to 3rd parties.  They can also be used to validate newly acquired older plants. In this context, older refers to facilities constructed prior to 1987, the year ASME rules for brittle fracture were introduced.

INSPECT's MSOT Curves Compare Equipment Brittle Fracture Ratings to Process Conditions
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INSPECT Includes an Extensive Vapor Pressure Curve Library

Vapor Pressure Curves

Vapor Pressure Curves are sources of process information used by INSPECT to help determine a critical region of the integrity operating window. INSPECT combines equipment MSOT and Vapor Pressure Curves to help operators consider the risk of auto refrigeration induced brittle fracture and ensure safe operations.

INSPECT provides a Vapor Pressure Curves library that covers fluids commonly used in the process industries. In Addition, INSPECT includes the ability to specify custom Vapor Pressure Curves. INSPECT plots the selected Vapor Pressure Curves on the MSOT curve to identify process conditions that exceed the equipment’s MSOT.

In addition to being plotted in the MSOT, Vapor Pressure Curves in tabular form are also presented in the summary report.

Creating a Master MSOT Curve in INSPECT

For more information on brittle fracture and auto-refrigeration please visit:

Prevent Brittle Fracture Failures by Following UCS-66 in COMPRESS and INSPECT

Auto-Refrigeration: When Bad Things Happen to Good Pressure Vessels by The National Board of Boiler and Pressure Vessel Inspectors

Auto-Refrigeration / Brittle Fracture Prevention And Process Safety Mitigation by Inspectioneering

Fitness-for-Service Forum: Minimum Pressurization Temperature (MPT) Curves: Why and How they are Going to Change by Inspectioneering

INSPECT Featured Capabilities

Part 3 API 579 Part 3 Ensure your operating procedures limit the risk of brittle fracture by automatically running Part 3 assessments. API 579-1 Part 3 MAT Curves Part 4 and 5 API 579 Part 4 & 5 Perform general and local metal loss assessments and quickly generate detailed reports. INSPECT performs API 579 FFS assessments and shows flaws on the 3D model Part 6 API 579 Part 6 INSPECT performs level 1, 2 and 3 pitting assessments and generates detailed API 579 reports with a click of a button. Combined Pitting and Local Metal Loss Flaws are Considered Part 7 API 579 Part 7 Perform Level 1 and 2 assessments from Hydrogen Induced Cracking (HIC) and Hydrogen Blister damage. API 579-1 Part 7 Hydrogen Cracking and Blister Damage Part 8 API 579 Part 8 Ensure that vessels subject to external pressure are within the allowed roundness tolerance with out-of-roundness assessments. API 579-1 Part 8 Out of Roundness Part 9 API 579 Part 9 Crack assessments quickly determines which crack-like flaws can be safely left in service and which require more investigation. API 579-1 Part 9 Crack-like flaw assessment Part 10 API 579 Part 10 Perform creep damage assessments by recording equipment operating histories and calculations. API 579-1 Part 10 Creep Damage Part 11 API 579 Part 11 Perform fire damage assessments and document conclusions in a consistent series of data entries and reports. API 579-1 Part 11 Fire Damage Assessments Part 12 API 579 Part 12 Perform Part 12 assessments and generate detailed API 579 reports. Level 1 and 2 dent, gouge and dent-gouge combinations are available. API 579-1 Part 12 dialog Part 13 API 579 Part 13 Model laminations and provide rapid results so you can make the necessary mediation decisions with confidence API 579-1 Part 13 Lamination Diagram API 510 API 510 Address in-service activities such as inspection, remaining life determination and repair. API 510 API 570 API 570 3D inspection data management and calculations simplify compliance with the requirements of the API-570 Code. API 570 API 653 API 653 Track tank thickness inspection measurements and provide calculation reports. API 653 Storage Tank Evaulations Gage Gage Integration Set up and retrieve inspection grids from thickness gages fast and easy. Thickness Gage Integration in INSPECT OSHA OSHA 1910 Meet the Mechanical Integrity requirements of OSHA1910.119 (j) and EPA Title 40 part 68.73. OSHA standards in COMPRESS Undocumented Undocumented Vessels Pressure Vessel Inspection Code requires owners to maintain permanent, progressive records as listed in API 510 Section 7.8 Undocumented Vessels in INSPECT IDMS The INSPECT IDMS Show condition monitoring locations (CML’s) and API 579-1 flaws directly on pressure equipment models. Inspection Data Monitoring System IDMS MSOT Auto-Refrigeration MSOT curves are employed to determine which process conditions put equipment at risk of failure by brittle fracture. Minimum Safe Operating Temperature (MSOT) curve in INSPECT Older Codes Old ASME® Codes Supported Increase vessel life automatically by using the higher allowable stresses per NBIC Section 3.4. Codes menu API 510 Pressure Relieving Devices Easily model pressure relieving devices (PRDs) on your fixed equipment. Easily model pressure relieving devices (PRDs) with INSPECT Excel Integration Excel Integration Export and import thickness inspection grids to and from Microsoft Excel. Excel Integration with INSPECT