News

T23 Tube Failure

During the startup of the triple-pressure HRSGs, plant staff noticed steam coming from the stack and a discrepancy between feedwater and steam flows.  On shutting down the unit a T23 superheater tube was found with a complete circumferential failure.  The failed tube was removed and the bore was plugged with some difficulty due to poor access and the uncommon material.

Read more: T23 Tube Failure

Understanding variations in Flow-Accelerated Corrosion Wear Rates in HRSG Evaporator Tubes

Very large differences in tube wall thinning rates by flow-accelerated corrosion (FAC), or in some cases fluid erosion, are observed in the low-pressure (LP) evaporator tubes of certain HRSG designs.  The tubes located near the duct wall and occasionally near the gaps between module bundles have more rapid thinning.  Tubes in a given row nominally should have very similar process conditions, both on the gas-side and on the waterside.  Different wall thinning rates mean that process conditions differ across the tube row. 

Read more: Understanding variations in Flow-Accelerated Corrosion Wear Rates in HRSG Evaporator Tubes

Role of Boiling Mode and Rate in Formation of Waterside Deposits in Heat Recovery Steam Generator Evaporator Tubes

Waterside Deposits in evaporator tubes have been an issue in steam generators as long as boilers have been used. Substantial experience in deposit formation and management has been gained in conventional goal and oil/gas boilers over time. The role of boiling modes in the steam generator tubes is very critical to areas of deposit formation. 

Read more: Role of Boiling Mode and Rate in Formation of Waterside Deposits in Heat Recovery Steam Generator Evaporator Tubes

HRSG Condition Assessments Identify CAPEX, Maintenance Priorities

As combined cycle gas turbine plants are called upon to play a larger and more flexible role in the generation mix, it’s important to schedule a comprehensive assessment of major components at key intervals to ensure reliable operation.

Read more: HRSG Condition Assessments Identify CAPEX, Maintenance Priorities

ASME B31.1 Covered Piping Systems' Mandatory Requirements

Since 2007, the ASME B31.1 Power Piping Code has included mandatory requirements on the Operation and Maintenance (O&M) of Covered Piping Systems (CPS), previously called High-Energy Piping.  The main concern is that the safety of these systems is very dependent on good O&M, which justifies its inclusion in the Construction Code.  There is room for flexibility depending on individual circumstances but the responsibility is squarely laid on the Operating Company.

Read more: ASME B31.1 Covered Piping Systems' Mandatory Requirements