Con Edison: steam operations - knowledge center: faqs

knowledge center: FAQ

Questions from our steam customers touch on everything operational-from water hammer to wet steam. Browse these pages to learn how steam works and how to make it work for you. If you have more questions, let us know. We'll post the answers.

	1. Where does Con Edison supply steam?
	2. Why does steam rise out of manhole covers?
	3. How often should customers check their traps?
	4. What can cause a trap to fail?
	5. What are some of the signs of a failed trap?
	6. What type of traps does Con Edison use?
	7. Can you get steam from air conditioning? If so, how?
	8. At what temperature should a steam room be during or after venting?
	9. Where is the “shut off” valve located?
	10. Which is better-- Flexitallic or Teflon Gaskets?
	11. How often are meters checked for malfunctions in customer buildings?
	12. Should Con Edison be contacted in the case of a direct replacement job?
	13. Who would support or certify the safety of use of a given steam supply for use in applications where the steam comes in contact with food?
	14. How much does Con Edison charge for repairs?
	15. What is condensate?
	16. What is water hammer?
	17. What should you do when water hammer is suspected and banging is heard?
	18. What causes steam pressure fluctuation?
	19. What are behind-the-meter services?
	20. During an outage which valve should be shut down - the inside valve (house) or the street service valve?
	21. Does Con Edison's Steam Operations operate valves after 12:00 midnight?
	22. How do you know if you have "wet" steam?
	23. If you have "wet" steam, do you install a blow valve?
	24. Should there be a pressure gauge in the building near the main valve?
	25. Are the pipelines in the street cast iron?
	26. How thick are the pipes?
	27. Who is responsible for the traps before the steam meters?
	28. What does the underground equipment used to distribute steam in Manhattan look like?
	29. How do I submit my resume?
	30. What kind of benefits does Con Edison offer?
	31. How can I learn more about Con Edison?

1. Where does Con Edison supply steam?

We supply steam to customers from the southern tip of Manhattan to 96th Street on the west side and 89th Street on the east side.

2. Why does steam rise out of manhole covers?

Steam can come from manholes for several different reasons. The most common is water infiltration into the manhole. Water comes in contact with the hot steam main and causes vapor. Another source is leaks, either within the manhole or on buried piping between manholes. There is no "natural" venting process.

3. How often should customers check their traps?

Manufacturer recommendation: for maximum trap life and steam economy, a regular schedule should be set up for trap testing and preventive maintenance. Trap size, operating pressure, and location determine how frequently traps should be checked. Suggested trap testing frequency is twice a year, at a minimum.

4. What can cause a trap to fail?

Steam cuts, dirt, or warped discs can cause the trap to fail open. This failure causes a steady stream of steam to be discharged into the condensate header. If a trap is allowed to blow, it can cause the premature failure of other traps discharging into the same condensate line by raising the pressure in the condensate discharge header.

If there is air in the piping, this can cause a trap to fail closed which can create a dangerous condition. It is important to slowly bleed and drain all lines as they are energized so that both air and water are removed.

5. What are some of the signs of a failed trap?

Signs of a failed trap include

Cold Trap – trap fails to discharge condensate
No condensate or steam coming to trap – plugged strainer, valve closed in line to trap, or pipe line/elbows plugged upstream of trap
Worn or defective mechanism
Trap body filled with dirt – install strainer or remove dirt/blowdown
Trap constantly discharging: trap valve fails to seat, trap too small

6. What type of traps does Con Edison use?

Con Edison uses Thermodynamic disc traps. The approved products are:

Spirax-Sarco TD52 - Barstock version
Gestra DK 57 - Forged version

7. Can you get steam from air conditioning? If so, how?

No, but you can produce air conditioning with steam using one of two processes:

Steam absorption
Steam driven turbine

8. At what temperature should a steam room be during or after venting?

Steam room temperature should not exceed 100°F.

9. Where is the “shut off” valve located?

There are “shut off” valves located in various places throughout the building:

Outside street service valve
Inside service valve (ISV, first valve in the building),
Meter inlet and outlet stop valves
Trap inlet and outlet isolation valves
Pressure reducing station inlet and outlet stop valves,
Steam equipment isolation valves

10. Which is better -- Flexitallic or Teflon Gaskets?

Teflon gaskets can’t be used when temperatures approach or exceed 500°F. Since there are no areas in the customer premises with temperatures this high, reinforced Teflon gaskets are fine for most applications. Flexitallic gaskets are required for high temperature and high-pressure applications or when the equipment manufacture has specified they be used. In some cases, the flange has been designed with a tongue and groove cut for a specific gasket. Follow the equipment manufacturer’s recommendations.

11. How often are meters checked for malfunctions in customer buildings?

EDP meters are calibrated annually
Vortex meters are calibrated every 5 years
Shuntflow meters are overhauled every 3 years

12. Should Con Edison be contacted in the case of a direct replacement job?
Yes. Call 212-683-8830 to schedule steam outages.

13. Who would support or certify the safe use of a given steam supply in applications where the steam comes in contact with food.
The FDA has a regulation governing the production of steam for food service and Con Edison complies with this regulation. The regulation is CFR 173.310 Boiler water additives. This regulation can be found online at http://www.access.gpo.gov/nara/cfr/waisidx_02/21cfr173_02.html

Note that this regulation restricts the additives (to a short list of additives often found in food), which may be used in boilers producing steam. There are some additives listed in the regulation, which may be used as long as their concentration in steam is measured and the steam has no contact with milk. Con Edison does not use any of the additives that have restrictions on their use.

14. How much does Con Edison charge for repairs?
We do not advertise and we are not looking to take work away from others. We do meter room repairs - replacement of flange gaskets, valve packing, etc., and we inspect and provide an estimate based on labor-hour rate plus materials. You only pay what the job costs. Labor cost: - $93 per hour from 7:30 a.m. to 3 p.m., Monday through Friday, excluding holidays, and $111 at all other times.

15. What is condensate?
As steam cools, it changes state from vapor to liquid. This liquid water is called condensate. It is advisable to remove this condensate from steam pipes. Automatic valves called traps remove the condensate and help ensure safety and prevent erosion of pipes and other equipment.

16. What is water hammer?
When condensate is not removed effectively from steam pipes, water hammer can result. It usually causes banging noises in the pipes. The most common type of water hammer is a traveling slug of water that impacts a fitting in the pipes, water in the steam line, or steam pockets in a return line.

17. What should you do when water hammer is suspected and banging is heard?
Shut the steam down and call Con Edison. Our Steam Distribution personnel will provide the necessary assistance.

18. What causes steam pressure fluctuation?
Steam pressure fluctuation most likely happens when there is a malfunction in the pressure-regulating valve. This should be attended to immediately. Con Edison can supply behind-the-meter support and repair these malfunctions. For more details, click on Maintenance & Services.

19. What are Behind-the-Meter Services?
Behind-the-meter services include repairs as well as temporary turn off/turn on of steam service. Con Edison provides 24-hour coverage for special services, including replacement of flange gaskets, valve packing, screwed piping, and welding. An inspection will be made and an estimate of the cost of labor and materials provided.

20. During an outage which valve should be shut down – the inside valve (house) or the street service valve?
The best practice is to close the valve that is connected to the minimum amount of steam piping. This reduces the chances of developing leaks and eliminates corrosion.

21. Does Con Edison's Steam Operations operate valves after 12:00 midnight?
We have a 24-hour staff, 365 days a year. We schedule our work to minimize customer inconvenience.

22. How do you know if you have "wet" steam?
Steam is considered "wet" when a small test valve is opened and excessive condensate is seen—especially when an object is placed in front of the valve. We typically deliver steam at a quality of 98% dryness, meaning that there can only be 2% moisture content.

23. If you have "wet" steam, do you install a blow valve?
No. Traps must be installed at all low points. These traps must be properly sized. If there is sensitive equipment on the line, a steam separator could be required. Call Con Edison to work with you.

24. Should there be a pressure gauge in the building near the main valve?
There is no code requirement for gauges; however, it is helpful to have a pressure gauge installed on each side of pressure reducing valves. Installing one on the steam station or near the main valve also is a good practice.

25. Are the pipelines in the street cast iron?
We replaced all of our cast iron pipes and fittings with steel pipes during the 10-year Steam Enhancement Program that was completed in 1999.

26. How thick are the pipes?
Pipes rated for 200 pounds per square inch (psig) are schedule 40, or 3/8" thick. Pipes rated for 400 psig are 1/2 " thick.

27. Who is responsible for the traps before the steam meters?
Con Edison is responsible for all traps before the steam meters. All traps after the steam meters are the responsibility of the building owners. Con Edison provides behind-the-meter services that include steam leak repairs and trap maintenance inspection. For more information click here.

28. What does the underground equipment used to distribute steam in Manhattan look like?
To see a diagram of the underground steam system, click here.

29. How do I submit my resume?
To apply for employment at Con Edison Company of New York:

Review the job openings at our Careers Web site;
Select the position best suited to your skills and experience;
Click the Click to Submit your Resume link to access our online resume-builder application.

30. What kind of benefits does Con Edison offer?
As a Con Edison employee you will receive a wide-range of benefits designed to provide protection for you and your family and assist you in maintaining greater financial security during your years of employment and after you retire. Here's a list of just some of the benefits we offer:

401K plan
medical
dental
vision
insurance
pension plan
tuition assistance
child care and eldercare assistance
paid vacations
paid holidays

31. How can I learn more about Con Edison?

Con Edison is a subsidiary of Consolidated Edison, Inc. [NYSE: ED], one of the nation's largest investor-owned energy companies, with approximately $13 billion in annual revenues and $28 billion in assets. The utility provides electric, gas and steam service to more than 3 million customers in New York City and Westchester County, New York. For additional financial, operations and customer service information, visit Con Edison's Web site at www.coned.com.

If you have any questions, send us an email at
steam@coned.com, and we'll answer them.