Prevent Valve Delamination in Conventional Power Plants

Emerson's Paolo Tomaini


Author: Paolo Tomaini

Conventional power plants are being disrupted by an increasing demand for renewable energy. The priority in providing energy to the grid associated with the intermittent intrinsic nature of the renewable energy output is creating a shift from base-load power down to cycling in traditional plants and causing failures.

The demand for renewables is only expected to grow over the next few decades, leaving conventional plant operators to adapt and upgrade their facilities, or suffer failures and their ramifications.

Valves play a major role in plant uptime in conventional plants. Valves manufactured 10 to 15 years ago, however, were not specified to carry the intermittent or low-loads duty of today’s operations, resulting in hardfacing wear. Thus, one of the most impactful steps in minimizing failures is evaluating the plant’s critical valves to identify potential delamination issues.

I suggest that operators should consider three key questions when assessing the risks of premature failure. Firstly, what was the original design specification for the installed valve? Secondly, what was the original valve manufacturer’s practice for hardfacing? And finally, is repairing these valves a definitive solution, or should they be replaced?

Signs of delamination in critical valves requires a complete redesign of the hardfacing process to help reinforce the base material of the valve and ensure it can withstand the new operating conditions. Operators should follow these steps for a successful hardfacing redesign:

  1. Identify a trusted and experienced valve manufacturer to redesign this process based on application conditions, base material/hardfacing combinations, and proper welding technologies and procedures
  2. Inspect the hardfacing condition of the installed valves, and prepare a replacement plan
  3. Specify a more robust hardfacing process for all new valves to be installed

The subsequent forced outages can cost end users as much as USD 250,000 per day in lost revenue in large coal-fired power plants, for example. So, in addition to bringing plant operations up to standard with the ability to withstand new performance requirements, end users who properly implement a plan to prevent delamination will avoid forced shutdowns, prevent revenue losses, save money and time on maintenance, and have the assurance of a long-lasting solution for the present and future service.

From Jim: Paolo will be a speaker at the upcoming Valve World Expo in Düsseldorf, Germany. You can listen to his presentation on valve delamination at 11:50 a.m. in room 3 on Thursday, November 29.

You can also connect with more valve experts in the Valves, Actuators & Regulators group, or power experts in the Power industry group in the Emerson Exchange 365 community.

Posted Friday, November 16th, 2018 under Final Control Element, Power.