Steam target shooting
Thread Content
At present, one set of hydroprocessing units is in operation; it has been half a month since steam was supplied for testing, yet the test pieces have not passed the inspection. It was then discovered that low-pressure steam is being used. Could it be that the low steam pressure is the cause of this issue? So what are the requirements for purging steam for a 3.5MP steam pipeline?
This post was last edited by ylb913 on 2015-6-8 at 11:59. 1. I personally participated in only one shooting test using a 35kg steam pipeline; below are the relevant details from our testing plan: During pipeline purging, a rotational and segmented purging method was employed, with a purging shooting coefficient of not less than 1 (Purging shooting coefficient = square of the steam flow rate used for purging and shooting × specific volume of steam during purging and shooting / square of the steam flow rate at rated load × specific volume of steam at rated load). It is usually around 55%-60% of the total steam consumption, with the steam amount used for purging at approximately 8 t/h. Before installing the target plate, perform two pressure-stabilizing purges and two pressure-reducing purges, and determine the timing for installing the target plate based on the flow conditions in the pipeline. The steam purging is carried out in a cycle of pressure increase – pressure stabilization – and then pressure reduction, as follows: heating the pipes for 3–4 hours (the first time) – purging at 8 t/h for 20 minutes – cooling for 1 hour (or to below 100°C) – purging at 8 t/h for 15 minutes – cooling for 12–18 hours – heating the pipes again for 2–3 hours – purging at 8 t/h for 15 minutes – cooling for 1 hour – purging at 10 t/h for 15 minutes – stopping the steam supply to install the target plate – purging at 8 t/h for 10 minutes – another 10 minutes of purging at 8 t/h – stopping the steam supply to remove and inspect the target plate; if it does not meet the requirements, the process is repeated with purging and targeting after cooling for 12–18 hours, until the target plate meets the standards. 2. We use 35kg of steam for operation. 3. The requirement for target shooting is to do so at the rated steam flow rate; in practice, however, due to pressure reduction, the shooting is carried out at a flow rate that is not less than the rated value. 4. Before steam purging and testing, we hit each weld with a hammer – I didn’t see this process with my own eyes, but I think it must be very important! 5. We succeeded in shooting at one target, which corresponds to a pipeline without any branches, and it is relatively simple.
Medium-pressure steam is recommended for steam; tap the pipe wall during purging
We all use compressed air to shoot targets; be careful not to get burned by steam.
Generally, plate forming is done with medium-pressure steam; low-pressure steam is only used for purging
Target shooting areas generally require a very high level of cleanliness, similar to that at the inlet of steam turbines. When shooting at targets, pay attention to the temperature of the medium-pressure steam; at the beginning of the purging process, it is possible to tap on the pipe walls
1. Use steam as required by the system whenever possible. 2. Perform flushing with a high flow rate. 3. Quickly open the target valve after pressure buildup
Our unit operates at a steam pressure of 3.82 Mpa, and the steam testing has been ongoing for 23 days; our steam system has strict requirements. The regular blasting method is employed, with the target plate being checked every 2 hours toward the end of the blasting process.