By creating a formalized procedure that you can refer to each time you start-up your vessel, you are not only ensuring your equipment will run safely, but you are maintaining a safe work environment for your employees.
We’ve compiled a Vessel Start-Up Checklist, free for you to download and use.
We’ve outlined some of the questions and action steps you need to address as you prepare your vessel for start-up and why each step is important.
General:
Is the nameplate uncovered and all stampings clearly visible? -
Your vessel’s nameplate is like its identification card and contains the following information:
· Manufacturers Identification Number (Serial Number)
· National Board Registration Number
· Vessel Design Pressure
· Vessel Design Temperature Range
· Vessel Capacity
· Year Vessel Fabricated
· Type of Glass Lining
As a best practice, we recommend that you copy this information and store it with other important data about the vessel in the event that the nameplate gets lost or damaged.
Are sight glasses free of any scratches, chips and/or cracks? -
Damage to the sight glass can be compounded when the vessel is pressurized, and you don’t want to run the risk of contaminating your product. Although rare, sight glasses can incur damage during transportation if the equipment is mishandled, so a quick visual inspection to ensure it’s intact is an easy but necessary task.
Is the internal cross-bracing removed?
New vessels are usually shipped with the agitator/drive system and baffles installed. Diagonal support structures help to protect these components from moving around during transportation as well as to keep the internal glass lining safe. All cross-bracing should be removed as soon the vessel has been installed into its final destination and prior to installation of additional components and before running the agitator.
Mixing Components:
Is the agitator runout less than 0.010” just above the shaft seal housing? -
On any type of rotating machinery, you should occasionally check for any deviation in the shaft rotation. Any stray from the centerline is known as runout. DDPS allows for a deviation of up to 0.010” – anything greater than suggests the agitator was not installed correctly and needs to be adjusted.
Does the agitator turn clockwise or counterclockwise? -
DDPS agitator blades are designed to be used in either direction. Make sure they run in the correct direction for your process, so they produce the anticipated mixing effect. Running the agitator the wrong way can not only affect your reaction, but possibly compromise your entire process if operated incorrectly. This is especially true in the case of GlasLock blades, which are installed at specific angles to help achieve your optimal mixing results.
Have the vessel and accessories been spark tested? -
As part of our Quality Control measures, new vessels and other glass-lined components are spark tested prior to shipment. We recommend that you perform follow-up inspections on an annual basis for agitated vessels and once every 1-2 years for non-agitated vessels (Note: this is an estimated time period and can fluctuate based on your process specifications as well as other factors). The type of spark testers that you use will depend on if the equipment is grounded. For more information on spark testing consult our Glass-Lined Equipment Inspection eGuide.
Is the baffle straight and in line with the agitator? –
The positioning of the baffle in relation to the agitator is crucial to accomplish effective mixing. It’s important to check that your baffle is installed correctly and situated on the right nozzle so that the two components work cohesively.
Drive System:
Ask yourself the following yes/no questions when you are inspecting your drive system prior to start-up. Actions should be taken to fix any leaks or other issues that present themselves during inspection of this component:
· Are there any oil leaks at the agitator or gear drive seals?
· Is the gear drive oil level at the correct level on the dip stick?
· Is the gear drive free of any excessive noise or temperature?
· Does the drive have the recommended lubrication?
· Is the nitrogen connected to the seal housing with a positive pressure differential?
Nozzles:
Are the nozzle loadings within allowable limits? -
There are limitations to the net forces that nozzles can be subjected to. Make sure all connected equipment and piping are aligned properly, keeping in mind that you need to account for thermal expansion where applicable.
Do the inlet nozzles have dip pipes or nozzle liners? -
Dip pipes are often installed on an inlet nozzle for baffling, sampling, and/or temperature measurement. PTFE nozzle liners are typically used to protect the nozzles of glass-lined vessels from corrosive materials.
Are the agitating nozzles positioned properly? -
When your vessel was manufactured, the site of the agitating nozzles on the vessel was selected to enhance the turbulence objective. Confirm that the nozzles are located where they should be to ensure process optimization. Agitating nozzles are installed in the vessel jacket inlets to promote the flow of the jacket media used. Make sure they are all going in the same direction.
Instrumentation:
Is the RTD (Resistance Temperature Detector) wired up? -
Although DDPS temperature sensors can be externally removed while a vessel is in production, upon start-up you want to inspect your RTD and make sure the wires are in place to provide you with immediate temperature measurement. Many processes are sensitive to even slight deviations in temperature, so you’ll want to ensure this instrumentation is up and running when your vessel is ready to go.
Manway:
As the main opening to the vessel, the manway needs to be inspected for several items, including:
· Is the manway cover closed and gasketed?
· Are there any leaks at the gasketed joints?
· Do nozzles/manway have AFII gaskets?
· Are the correct number of clamps used?
· Are clamps tightened in the proper sequence and torqued to the correct value?
Vessel Body:
Are the vessel contents free of any sparks (electrostatic discharge)? -
It is a natural phenomenon for static charges to buildup in glass-lined process equipment, especially when your process involves agitated non-conductive liquids or falling powder additions. When left unattended over time, this may lead to the breakdown of the glass lining. An effective way to identify this problem is by taking measurements using an electrostatic voltmeter. This simple device can measure electrostatic voltage up to 30,000V.
Are there any visual changes in the repair plugs (if applicable)? -
If you answer “yes” to this question, it could be a red flag that your repair plug is not secure. If you have any doubts, take a picture of it and contact DDPS. A service representative can help you decide if there is a possible issue that needs to be addressed.
Is diaphragm outlet valved or tied into trapline? -
It seems rather foolish to have a vessel all ready to go and forget to check that the BOV is in place and closed! But it has happened before so it’s always smart to check that the valve is installed properly and in the closed position. Alternately, a trapline can be connected to the vessel bottom opening to contain solvents and ensure there’s no leakage.
Jacket:
Is the jacket medium free of any acidic product? -
Various heating and cooling mediums are often used in glass-lined vessel jackets, ranging from steam, water, glycol solutions and brines to a wide range of synthetic heat-transfer fluids. In a typical application, steam, cooling water and a chilled solution might all be used in the same jacket at different points in the reaction cycle. This is very efficient from a production standpoint, but potentially damaging in its effect on the jacket lining and vessel exterior. The more acidic the jacket medium, the higher the rate of corrosion. Check to make sure the fluid you use for your process is in the acceptable neutral range.
Is the vent hooked up? -
The vent in the jacket is required to allow the air to escape the jacket when filling it with liquid. If the vent is not opened during filling you will run the risk of air pockets in the jacket, which will lead to poor performance and other potentially harmful problems.
Process Specific:
Are all chemicals to be used compatible with the glass lining and repair plugs (if applicable)? -
If you did your due diligence prior to purchasing your equipment, the answer this to this question should undoubtedly be “yes”. However, it is still something to keep in mind, especially if your existing vessel was brought out of commission to be used in a new process. While glass lining is known for its superior corrosion resistance, there are a few chemicals that need to be avoided, namely hydrofluoric acid and hot concentrated phosphoric acid.
Are precautions in place to prevent low volume mixing at agitator blade level for an extended period of time? -
The agitator should never be run at full speed with the liquid level at the agitator blade level. When the agitator is run with the fluid in the vessel at approximately the same level as the blades, fluid flow can cause the shaft to “skate”, resulting in excessive stresses and runout in the seal area and upper end of the agitator. This can cause premature seal failure and even glass damage on the agitator itself. The simple fix is to make sure there is the right volume of product in your vessel before turning on the agitator. If this becomes a regular problem, then it’s time to look into getting a different sized reactor to meet your process needs.
Are the temperatures of all chemicals to be added within manufacturer’s allowable temperature changes? -
Your vessel’s nameplate lists the temperature limitations, but it doesn’t show the allowable temperature changes, a factor that you need to consider when operating glass-lined equipment. To determine a safe temperature change, reference our handy “Maximum Allowable Thermal Shock – 3009 Glass” chart and you can easily determine the safe temperature differentials for 3009 glass lining. In general, the higher the operation temperature, the lower the safe temperature differential. If you are ever unsure it is always best to consult with a professional at DDPS who can give you the right guidelines.
The Vessel Start-Up Checklist is an essential tool for safe vessel operation. Download your free copy and use it each time you start-up your vessel to ensure not only safety but process optimization. And if any issues arise that require professional assistance, contact De Dietrich Process Systems’ service team and a representative can provide technical support or you can schedule service if additional onsite assistance is required.