Managing the Power Piping in CCGT Plants
Risk of failure and attendant personnel safety concerns are always present when operating highly-pressurized systems. Over the years, the occurrence of catastrophic events has driven improvements in construction codes and updated recommendations for O&M practices. As part of this trend, expanded requirements for operations and maintenance (O&M) were recently added to the ASME Code for Power Piping—ASME B31.1. The “Chapter VII Operation and Maintenance” was created in 2007 to prescribe guidelines that promoted early failure detection and overall safety. This was a fundamental change to the scope of B31.1, which up until then was strictly a design code; going forward, it now serves a dual purpose…
Read the full story by our colleague Robert Rosario, published online in Power Magazine here.
Boiler Preservation Engineering
OEM or industry guidelines for Boiler or HRSG waterside and gas-side preservation (or “layup”) are useful but typically don’t go further than general advice on the different available options (wet vs. dry etc.). The difficulty is in moving from the general to the specific for a given plant.
Tetra can define viable preservation options and help you choose an optimal strategy from among these that fits your budget and operational constraints.
If desired, Tetra will then develop a detailed engineering specification for your preservation system.
For more information about the service click here.
Technical Tidbits from the Tetra HRSG Inspection Planning Guide
The inspection of drums is a key element in determining the general condition of the waterside pressure boundary of the HRSG components and the quality of the water treatment program. They are a “window” on what the inside of the water-filled or steam and water-filled tubes and headers in the various pressure circuits (HP, IP or LP) might look like. Basic inspection is visual, yet often complemented by UT, and PT/MT examinations.
One of the key items of interest is surface passivation. The HP drum should typically have a dark grey adherent surface layer, characteristic of magnetite, below the maximum waterline. Above the maximum water line there may be some light red coloration, indicating a mix of magnetite and hematite. Yet surface color can deceive, drums with “abnormal” color may simply reflect a specific water chemistry and process condition history. The experience of the inspector comes into play in these cases, to decide whether what is observed is indicative of a real problem or simply reflects a harmless difference.
Senior Engineer Mark Taylor from Tetra’s European office enjoying some quality Steam Drum time during a recent HRSG inspection campaign.