Contaminates and left-behind construction materials that find their way into boilers, turbines, pipelines, superheaters, and other equipment are the number one cause of downtime for new systems. Steam blowing is an effective, safe method for ensuring your systems are not threatened by construction debris, mill scale, and other contaminants.
By performing a steam blow, you are extending the life of your equipment, ensuring systems meet ISO cleanliness standards, and keeping your project on-track. Other benefits to steam blows include being environmentally friendly (do not require chemicals), minimal disruption to other critical path operations, and then can usually be performed in 7-12 days, which is also cost-effective.
Learn more about our steam blowing capabilities below or reach out to a certified technician for a quote.
RIG’s Steam Blowing Procedure
A typical steam blowing project with RIG progresses as follows:
- During an initial call, we extract critical project specifications and key information from you
- One of our engineers performs a site walk down to thoroughly plan the steam blowing procedure including the number of stages, type of blow, temporary piping requirements, and other engineered features of your specific plan
- Any recommended pre-blowing services such as chemical cleaning, hydraulic line testing, and plate checks are performed
- Our team takes full responsibility for the blow, shipping all necessary equipment and running the job on-site. A typical steam blow follows one of two methods:
- Impulse/puffing steam blows
- Boiler pressure is slowly raised to a pre-calculated pressure level and firing rate is increased
- The water level in the drum is brought slightly above normal because during blowing it will drop significantly
- A low pressure verification blow is performed to ensure proper system setup for temporary piping and anchors.
- Temporary piping is used from a temporary steam turbine exit with water injection along the pipe to help quench and reduce the volume of steam before it reaches the steam exhauster/silencer. This helps reduce the noise to a level more acceptable to the OSHA standard.
- Temporary valve opens to blow through the superheater, main steam pipe and temporary pipe
- Additional rounds of high-pressure ‘puffs’ are sent through the system. Steam blows are conducted without target plates until steam color becomes clear. Then preliminary target or impact plates are placed to capture particles going with the steam. RIG impulse steam blow uses the latest in fast opening hydraulic actuated valves that are hard surface coated to withstand debris many repetitions of opening and closing.
- While blowing, fire is put out and pressure is dropped, ensuring proper temperature differential to dislodge any adhering material
- Steam blowing valve is closed and boiler is started
- Final target plate of turbine blade is placed once preliminary target plate is in acceptable form
- Blowing continues until indentations are acceptable to turbine manufacturer guidelines
- After mainstream line is complete, other stages are done in the similar fashion
- Low pressure continuous blowing
- The process for continuous blowing is similar to the impulse blow method, but steam is produced by the boiler or heat recovery system generator and then allowed to escape through a temporary exit into piping.
- Additionally, pressure and temperature is continuously maintained during this method, which is easier on plant equipment
- The drawback to this method is that it is not quite as effective as the impulse method at removing debris because piping does not expand and contract as much, which can be key to dislodging some contaminants.
- Once the appropriate steam blow has been performed, we verify cleanliness levels with a visual inspection
- Temporary set-ups are then dis-assembled and full project documentation is turned over to you
- Impulse/puffing steam blows
Our team of pre-commissioning service experts ensures a safe and effective steam blow at your facility by creating a thorough work-site plan and documenting all potential hazards before the blow begins. We pre-plan, monitor, and track every detail to make sure no unnecessary thermal stress or pressure is used on your system, boiler or sensitive equipment.
OCI Methanol Beaumont: Plant Restart and upgrade, Continuous Steamblows, Oilflushing, Line Blowing and Chemical Cleaning.
Longview Power Station Maidsville, WV – New Coal fired power plant – RIG performed chemical cleaning of the Boiler and Pre-boiler piping systems and Impulse steam blows.
Jaguar Coal Fired Power Plant – 2 blocks Coal Fired Boilers- Performed chemical cleaning of the boilers. Hydrolazing on Steam, CCW, BFW and Condensate piping. Impulse steam blows.
Air Products Tees Valley Waste to Energy UK – RIG performed chemical cleaning of the HRSG’s, Hydrolazing of the Piping, Oilflushing of the CT’s / STG and steamblows of the headers and to the STG.
Hines Power Block Progress Energy Lakeland, FL – Chemical Plant Commissioning Project- New Combined Cycle project- Nooter Eriksen HRSG’s, Westinghouse CT’s and STG-Performed citric acid CC, Hydrolazing of all steam piping, airblows on Block 2 and continuous steamblows on Block 3.
What is steam blowing?
The blowing of steam through piping to remove debris from the pipe, cleaning steam lines to a steam turbine, cleaning plant expansion lines, or new installs. As the definition says, to steam blow a pipe requires steam to blow through the pipe. This pipe can be attached to a boiler or heat recover steam generator, and the other end of the pipe can be attached to a steam turbine.
Are there different types of steam blowing?
Continuous low pressure steam blow, where steam is produced by the boiler or heat recovery steam generator and allowed to escape the temporary steam turbine exit into temporary piping. The low pressure method allows for a continuous steam pressure and temperature on the permanent plant equipment. The required steam blow is pre-calculated to use about 45 to 55% of the maximum steam flow at a low pressure. That low pressure is whatever the back pressure of the permanent piping is. This methods works due to the fact that high temperature steam at low pressure has a much higher specific volume than a corresponding temperature steam at high pressure. Therefore, the multiplier in the steam flow calculation is greater in a low pressure situation.
Impulse steam blows: The accepted method for a steam blow per NEMA 23 and NEMA 24 is an impulse blow where steam is bottled up in the boiler attached to the opposite end of the steam piping to the steam turbine. A break out point at the steam turbine is established and a quick opening valve is attached to this break out and a short piece of pipe is attached to vent the steam in a safe direction.
Impulse blows can be done with either water injection into the temporary piping or dry silencers which require no water injection. The circumstances for utilizing each are as follows:
Dry Silencers are utilized where no personnel will come in contact with the temporary piping, the temporary piping is at full exit temperature, this will require the craft people to be quarantined from the area where the steam piping will be routed.
Water injection type silencers do require injection of water down stream of the permanent piping tie-in, as a result the temporary piping temperature is reduced dramatically. This is the safest application for congested work areas that will contain craft personnel.
How long does a steam blow procedure take?
The length of a steam blow varies depending on what is being treated, however average steam blows take somewhere around 2 weeks. To shorten this timeline, hydrolazing before a steam blow can shave 5-8 days off the steam blow.
Continuous steam blows can usually be completed much faster than an impulse steam blow. An impulse steam blow takes many valves closing and openings to exhaust the steam at a good cleaning force ratio for only short sections at a time, whereas, a continuous steam blow the steam is always flowing and the cleaning force ratio becomes greater down the line as the pressure drops towards the exit. An impulse steam blow is just short puffs
What regulations do you follow during steam blows?
Generally when the piping is attached to a steam turbine the steam turbine manufacturer has already developed a guideline as to how this piping must be steam blown. There are several general methods already established to complete this and of these NEMA 23 and NEMA 24 are two of the guidelines generally referenced. These are general guidelines and Section 8 of each NEMA procedure is identical as to method and purpose of the steam blow.
How do you reduce noise and high temperatures during steam blowing?
One basic precaution includes using dry silencers that don’t require water injection to reduce noise, which can make a huge difference in risk during the procedure.
To control noise, a steam exhauster/silencer is also used. In addition, temporary piping from the temporary steam turbine exit is used with water injection along the temporary pipe, limiting the volume of steam before it reaches the steam exhauster/silencer.
One way to control noise, limit temperature fluctuations, and speed up the process, is to use the continuous blowing method. In continuous blowing, there’s one continuous, low-pressure blow performed around the clock at a steady temperature and pressure.
Is steam blowing safe to perform on combine-cycle plants?
Steam blows can be safe to perform on combined cycle plants when properly planned and engineered. Specific considerations we make sure to cover when planning a combined cycle steam blow include:
- Establishing the correct number of stages to ensure each OTSG, HRSG and section of piping is addressed with the correct pressure
- Minimizing water requirements to avoid expensive temporary water-sources to be brought on-site if possible
- Thermal cycle planning for the fastest dislodging of mill-scale and debris with periodic cool downs during blowing
- OTSG and HRSG feed rates are planned for to correctly control steam flow during blowing
- Additional piping (more than normal) for sound control is often required during combined cycle blows, so we ensure this is engineered into our plans as well
Read more details about planning combined cycle steam blows here
When should I use air blowing vs. steam blowing?
Air blowing works in great combination with chemical cleaning, such as in power plant systems. The chemical cleaning solution will dissolve mill scale, and then the non-soluble particles that have been dislodged during cleaning can be removed via air blowing. Air blowing puts less direct stress on your system than steam blowing does, so if a chemical clean will be sufficient to remove mill scale, it’s easier on your system to combine it with air blowing.
Read more about the pros and cons of each method here