(no subject)
I had originally meant to post the following after my first day on the job. It instead languished inside my email inbox until now. So here it is!
Today I started my new job at Alstom Power, as real live engineer. Having been at Timmons Group since 2003, it has been some time since I went through the ‘first day’ experience, and I haven’t had too many jobs in the first place to experience it before. I’ve only worked at Precision Machine Works, Gillum Architects, Timmons Group, the Army, and now Alstom.
I’m going to be working in a department that deals with the testing and balancing of steam turbines and generator rotors for power plants. Specifically I am replacing a guy named Mike who is getting promoted out of his area of expertise. One of the big parts of testing is the setup. We have what’s called the spin pit, where parts are run up, and to do that they have to be adapted to our system and connected. So bearings, couplers, adapter plates and more need to be selected for the specific rotor or turbine. Mike was the guy who selected all these parts and had them ready for the arrival of the turbine or rotor. He’s also really the only guy who does his job, so his loss is going to leave a big hole. Thankfully there will be a period of overlap where he will help me fill his shoes. Later I can decide whether this is where I would like to be at Alstom, or whether I want to focus on the test engineer portion of the job.
This first day has been interesting. My boss just returned from vacation, so he wasn’t in until 1pm, and we just had a chat. Much to my relief he told me to take it easy for the immediate future, and get comfortable with the systems and file structure they have here. As Mike has been doing his job for sometime, there is a multitude of spreadsheets of data and drawing files that will be very helpful for me. Finding the right one at the right time is going to be the real trick. There are hundreds of different files and drawings for each style of part. I apparently have control of a rather large storeroom where all the physical pieces are kept, so I’m not sure how much of their maintenance and upkeep will be my responsibility or the responsibility of all the members of my group.
Alstom Power is a large international company, so on the positive side I will be able to get some benefits for a change (having always worked part time until today). That part I will gladly take!
It’s now been 2.5 months since I started here at Alstom Power, and I can look back at that naïve description and chuckle. I knew that I didn’t have too much of an idea of what to expect back then, but I felt confident I could handle it. I still feel confident, but I now have more of a handle on what exactly this job does. It’s a little more than just choosing the correct puzzle pieces for the job and making them fit. A lot of the rotors we test are common styles or ones we’ve tested before. But as I’ve seen, a lot of them aren’t! Since I’ve been here we’ve tested 6 rotors. One of those in particular was a bit of a headache. Let me walk you through the process.
It begins with Eric, my boss, being told the rotor will be coming here, and he lets me know. At this point we probably just know that it’s coming. Size, dimensions, weight; we don’t have this yet, so we really know nothing. At some point after us asking, we finally get some dimensions. The most important ones for me are the diameters and lengths of the journals (the part of the rotor that rides inside the bearing). Small ones are around 8” diameter, big ones are around 20”+. A properly sized bearing will be less than a 1/16” of an inch larger in diameter (depending on the size, a smaller bearing will have a smaller size difference, as it’s based on a percent, not a distance). Since not all rotors are created equal, or by the same manufacturer, this means we need to keep many bearings on hand. We have over 100. To change the size on a bearing if it turns out we don’t have one ready, we could bore out an undersized one, or buildup an oversized one, within reason. But sometimes you need to make an entirely new one, and that will run you around 5 weeks or so. Another factor is the loading. The bearing can only take a certain amount of kg/cm², or pressure, so heavier rotors need wider bearings to spread out the weight. The rotors can have big differences in weight (and everything else). A small rotor might weigh 13,000kg, a big one could be over 100,000kg. (That’s around twice as much for pounds, 50,000 to 200,000).
Once the bearing issue is settled, I start putting together a setup drawing. A rotor in the spin pit is installed by resting in the bearings, and being connected to the drive shaft with a drive plate. This plate will fit the coupling face of the rotor and either attach by bolting into threaded holes on the rotor, or attaching via coupling plugs if there are no threaded holes. As I learned the hard way, the sizing of this plate is crucial. The rotor has what is called a spigot, and that just means either an innie or an outie plug that our plate fits over. Just like the bearings, close fit here is important. If the rotor has a spigot 18” exactly, then our plate will have a matching circle only 0.0023” or less different. That’s 0.02 to 0.06mm difference. A closer fit will save a lot of time in setting up and doing the runouts of the rotor (how close everything is running to concentric). We have well over 100 plates, and some of them have numerous holes because they get used and reused until you can’t fit any more holes on them. But even then sometimes you need to make a new plate because there just aren’t any old ones that can be modified. For instance, if the rotor has a 270mm male spigot, I need a plate with a 270mm or less female spigot, so I can open it up to the right diameter. If all the plates that aren’t dedicated to a single rotor style and aren’t already swiss cheese have spigots bigger than 270mm, I’m out of luck (pretty much). With the drive plates go the coupling plugs. Some rotors, instead of having a pattern of boltholes have coupling holes. They’re still for bolts, they’re just for really big bolts, like 3 or 4” diameter bolts. So what we do is make a metal plug that fits that hole and also has a center hole for a smaller bolt to go through it into the plate. Now our rotor will turn. Other times, we might have both threaded holes and coupling holes. The only issue is that if we don’t use the coupling holes, we can’t have them open to the air, so we will either plug them if the plate doesn’t cover them, or leave them if the plate is big enough around to cover them up.
Some rotors have really long backends. The two sides are generally the drive side and the non-drive side, or DS and NDS, or DE and NDE. If the NDE side sticks out far from the bearing, we can’t have it unsupported, since it would wobble. Think of having a pencil in a drill. If it sticks out really far, the unsupported end is going to wobble around and not stay on center. So we add what’s called a stub shaft. This bolts to the NDE coupling face and in turn is supported by its own bearing. So if that’s required, that’s another part to select, or maybe more, if it needs an adapter plate and coupling plugs as well.
Once that’s all done, we have what are called baffle rings. The bearings are journal bearings (as opposed to ball bearings like smaller ones tend to be), so there’s a lot of oil. That oil can make a huge mess if not contained, or if it gets into electronics or heated areas, make a dangerous situation. It's kind of like putting your thumb on the end of a garden hose. So on each side of the bearing, baffle rings sit very close the surface of the rotor, so oil can’t escape and get flung everywhere. The baffle rings are held by the baffle housings. These are a handful of different sized slotted rings that allow us to (hopefully) work around the different sized rotors.
For the generators, we need to test the electronics. The rotors have an area of slip rings, which can kind of be thought of as the terminals on a battery. We measure through these slip rings how the rotor is performing. On some rotors (like an upcoming one) there are no slip rings, so we have to attach our own to the connections the rotor has. Which means more adaptors and fittings.
Obviously, there are also weights. The ultimate goal of the spin pit is to perform a high-speed balance. Just like the mechanic puts weights on your car’s tires to balance them, we put weights on the rotor. Now for a tire, you put weights in one plane: the ring around the inside of the tire. On rotors, it might be 2 planes or it might be 11 planes, running down the length of the rotor. So we have wedge weights, headless bolts, and many other types. When a rotor comes in we have to make sure we have the right type and enough of them to balance the rotor, and away we go.
So that’s kind of my job in a nutshell. It doesn’t take too long to determine what’s needed for a rotor, but if new or modified material is needed, then the time gets extended. Most of the time, we have weeks or even months to plan for a rotor. But that is not always the case. Last Friday I was informed we would be having a new rotor arrive in 2 weeks time. Thankfully I was given some basic drawings, but despite having bearings for the job, that’s all I know is good. Drive plate, couplings, baffle rings, all is TBD. I’m almost afraid that if things go well, they’ll ask why we usually need a long lead-time to get it done. But mostly I want it to go well!
It’s been a fun 2.5 months, and I expect it will continue to be so, especially after I get the hang of it, and feel a little less lost every time something new comes down the pipe.
Some shots of different rotors in the spin pit.
Balance weights.
A large collection of baffle rings...
..and bolts.
And plugs!
Today I started my new job at Alstom Power, as real live engineer. Having been at Timmons Group since 2003, it has been some time since I went through the ‘first day’ experience, and I haven’t had too many jobs in the first place to experience it before. I’ve only worked at Precision Machine Works, Gillum Architects, Timmons Group, the Army, and now Alstom.
I’m going to be working in a department that deals with the testing and balancing of steam turbines and generator rotors for power plants. Specifically I am replacing a guy named Mike who is getting promoted out of his area of expertise. One of the big parts of testing is the setup. We have what’s called the spin pit, where parts are run up, and to do that they have to be adapted to our system and connected. So bearings, couplers, adapter plates and more need to be selected for the specific rotor or turbine. Mike was the guy who selected all these parts and had them ready for the arrival of the turbine or rotor. He’s also really the only guy who does his job, so his loss is going to leave a big hole. Thankfully there will be a period of overlap where he will help me fill his shoes. Later I can decide whether this is where I would like to be at Alstom, or whether I want to focus on the test engineer portion of the job.
This first day has been interesting. My boss just returned from vacation, so he wasn’t in until 1pm, and we just had a chat. Much to my relief he told me to take it easy for the immediate future, and get comfortable with the systems and file structure they have here. As Mike has been doing his job for sometime, there is a multitude of spreadsheets of data and drawing files that will be very helpful for me. Finding the right one at the right time is going to be the real trick. There are hundreds of different files and drawings for each style of part. I apparently have control of a rather large storeroom where all the physical pieces are kept, so I’m not sure how much of their maintenance and upkeep will be my responsibility or the responsibility of all the members of my group.
Alstom Power is a large international company, so on the positive side I will be able to get some benefits for a change (having always worked part time until today). That part I will gladly take!
It’s now been 2.5 months since I started here at Alstom Power, and I can look back at that naïve description and chuckle. I knew that I didn’t have too much of an idea of what to expect back then, but I felt confident I could handle it. I still feel confident, but I now have more of a handle on what exactly this job does. It’s a little more than just choosing the correct puzzle pieces for the job and making them fit. A lot of the rotors we test are common styles or ones we’ve tested before. But as I’ve seen, a lot of them aren’t! Since I’ve been here we’ve tested 6 rotors. One of those in particular was a bit of a headache. Let me walk you through the process.
It begins with Eric, my boss, being told the rotor will be coming here, and he lets me know. At this point we probably just know that it’s coming. Size, dimensions, weight; we don’t have this yet, so we really know nothing. At some point after us asking, we finally get some dimensions. The most important ones for me are the diameters and lengths of the journals (the part of the rotor that rides inside the bearing). Small ones are around 8” diameter, big ones are around 20”+. A properly sized bearing will be less than a 1/16” of an inch larger in diameter (depending on the size, a smaller bearing will have a smaller size difference, as it’s based on a percent, not a distance). Since not all rotors are created equal, or by the same manufacturer, this means we need to keep many bearings on hand. We have over 100. To change the size on a bearing if it turns out we don’t have one ready, we could bore out an undersized one, or buildup an oversized one, within reason. But sometimes you need to make an entirely new one, and that will run you around 5 weeks or so. Another factor is the loading. The bearing can only take a certain amount of kg/cm², or pressure, so heavier rotors need wider bearings to spread out the weight. The rotors can have big differences in weight (and everything else). A small rotor might weigh 13,000kg, a big one could be over 100,000kg. (That’s around twice as much for pounds, 50,000 to 200,000).
Once the bearing issue is settled, I start putting together a setup drawing. A rotor in the spin pit is installed by resting in the bearings, and being connected to the drive shaft with a drive plate. This plate will fit the coupling face of the rotor and either attach by bolting into threaded holes on the rotor, or attaching via coupling plugs if there are no threaded holes. As I learned the hard way, the sizing of this plate is crucial. The rotor has what is called a spigot, and that just means either an innie or an outie plug that our plate fits over. Just like the bearings, close fit here is important. If the rotor has a spigot 18” exactly, then our plate will have a matching circle only 0.0023” or less different. That’s 0.02 to 0.06mm difference. A closer fit will save a lot of time in setting up and doing the runouts of the rotor (how close everything is running to concentric). We have well over 100 plates, and some of them have numerous holes because they get used and reused until you can’t fit any more holes on them. But even then sometimes you need to make a new plate because there just aren’t any old ones that can be modified. For instance, if the rotor has a 270mm male spigot, I need a plate with a 270mm or less female spigot, so I can open it up to the right diameter. If all the plates that aren’t dedicated to a single rotor style and aren’t already swiss cheese have spigots bigger than 270mm, I’m out of luck (pretty much). With the drive plates go the coupling plugs. Some rotors, instead of having a pattern of boltholes have coupling holes. They’re still for bolts, they’re just for really big bolts, like 3 or 4” diameter bolts. So what we do is make a metal plug that fits that hole and also has a center hole for a smaller bolt to go through it into the plate. Now our rotor will turn. Other times, we might have both threaded holes and coupling holes. The only issue is that if we don’t use the coupling holes, we can’t have them open to the air, so we will either plug them if the plate doesn’t cover them, or leave them if the plate is big enough around to cover them up.
Some rotors have really long backends. The two sides are generally the drive side and the non-drive side, or DS and NDS, or DE and NDE. If the NDE side sticks out far from the bearing, we can’t have it unsupported, since it would wobble. Think of having a pencil in a drill. If it sticks out really far, the unsupported end is going to wobble around and not stay on center. So we add what’s called a stub shaft. This bolts to the NDE coupling face and in turn is supported by its own bearing. So if that’s required, that’s another part to select, or maybe more, if it needs an adapter plate and coupling plugs as well.
Once that’s all done, we have what are called baffle rings. The bearings are journal bearings (as opposed to ball bearings like smaller ones tend to be), so there’s a lot of oil. That oil can make a huge mess if not contained, or if it gets into electronics or heated areas, make a dangerous situation. It's kind of like putting your thumb on the end of a garden hose. So on each side of the bearing, baffle rings sit very close the surface of the rotor, so oil can’t escape and get flung everywhere. The baffle rings are held by the baffle housings. These are a handful of different sized slotted rings that allow us to (hopefully) work around the different sized rotors.
For the generators, we need to test the electronics. The rotors have an area of slip rings, which can kind of be thought of as the terminals on a battery. We measure through these slip rings how the rotor is performing. On some rotors (like an upcoming one) there are no slip rings, so we have to attach our own to the connections the rotor has. Which means more adaptors and fittings.
Obviously, there are also weights. The ultimate goal of the spin pit is to perform a high-speed balance. Just like the mechanic puts weights on your car’s tires to balance them, we put weights on the rotor. Now for a tire, you put weights in one plane: the ring around the inside of the tire. On rotors, it might be 2 planes or it might be 11 planes, running down the length of the rotor. So we have wedge weights, headless bolts, and many other types. When a rotor comes in we have to make sure we have the right type and enough of them to balance the rotor, and away we go.
So that’s kind of my job in a nutshell. It doesn’t take too long to determine what’s needed for a rotor, but if new or modified material is needed, then the time gets extended. Most of the time, we have weeks or even months to plan for a rotor. But that is not always the case. Last Friday I was informed we would be having a new rotor arrive in 2 weeks time. Thankfully I was given some basic drawings, but despite having bearings for the job, that’s all I know is good. Drive plate, couplings, baffle rings, all is TBD. I’m almost afraid that if things go well, they’ll ask why we usually need a long lead-time to get it done. But mostly I want it to go well!
It’s been a fun 2.5 months, and I expect it will continue to be so, especially after I get the hang of it, and feel a little less lost every time something new comes down the pipe.
Some shots of different rotors in the spin pit.
Balance weights.
A large collection of baffle rings...
..and bolts.
And plugs!