Design Considerations for Equipment and Piping Layout: The Ins and Outs of Pumps

Design Considerations for Equipment and Piping Layout: The Ins and Outs of Pumps

This is the second in a four-part series on equipment and piping layout.  This article discusses the equipment layout considerations for pumps, as well as guidelines for the pump’s suction and discharge piping.

The first article provided guidelines for vessels, cooling towers, and compressors. Guidelines for piping and pipe rack layouts will be discussed in the third article.  The series concludes with the special requirements for heat exchangers, valves, and instrumentation.

Pumps Have Many Needs

Pumps move liquids and slurries from one location or piece of equipment to another, through piping that is under pressure. The material being moved can be hot, cold, or ambient temperature.  The suction and discharge lines are generally located on the side or the top of a pump.

Centrifugal pumps are most commonly used in industrial and commercial settings, although reciprocating, rotary, and diaphragm pumps may be preferred for particular situations. Most pumps are driven by electric motors.  Sometimes, steam turbines drive pumps that are used for backup during power failures.  Diaphragm pumps are driven by compressed air.

A primary consideration in pump layout is to place every pump close to the equipment that provides material to the suction inlet of the pump. Ideally, the suction piping is as short and straight as possible to minimize friction losses.

Another important consideration is that the location be consistent with the pump manufacturer’s specifications, as well any design and process requirements by the project owner, so that the pump provides sufficient suction and discharge pressure.

Past layout practices often located pumps under pipe racks. But in recent years, many pumps carrying flammable materials have been moved away from pipe racks to limit damage in case of a pump fire.

Mechanical engineers must also ensure that the pump location will:

  • Provide easy access for pump and motor repair, replacement, and regular maintenance. For example, ensure that pump lubrication and cooling systems can be properly serviced. Also, areas around pump seals and bearings need to be accessible for service.
  • Avoid potential obstructions in all directions. When everything is installed, will any pipes or valves be in the way? Make sure that the pump can be removed without removing the isolation valves.
  • Comply with the owner’s specifications for pump piping, especially straight run suction line requirements. Also, other codes may apply if the pump is used in fire water service.

Piping engineers must look at numerous factors when designing the pump’s suction piping and discharge piping. The following guidelines are a sample of some industry standards and good piping layout practices.

Pump Suction Piping

Suction piping is usually one or two line sizes larger than the pump nozzle. If the suction line is two line sizes larger than the pump nozzle, use a block valve that is one size larger than the pump nozzle.  Provide a drain between the block valve and the pump nozzle.

Keep suction piping as short and simple as possible to minimize friction losses and flow turbulence at the pump. The flow will be more smooth and uniform when following the API recommendation to have a straight run at least 5 pipe diameters (based on the nozzle size) between the nozzle flange and the first tee, cross, valve, or strainer. This will reduce the possibility of pump cavitation.  The forces and moments on the pump nozzles created by the suction piping also need to kept below manufacturer allowables.

Some other key considerations include:

  • Keep reducers as close to the pump as straight run requirements will allow. Use eccentric reducers, flat side up, on most pump suction lines.
  • Use long radius elbows, and minimize the number of elbows.
  • Install temporary strainers during startup if permanent strainers are not used.

Here are a couple of don’ts:

  • Do not have high points in pump suction piping. This will prevent vapor collection in the line.
  • Do not mount valves directly on pump flanges. Besides disrupting smooth flow, this will make it difficult to perform maintenance on the pump.

Pump Discharge Piping

Discharge piping is usually one or two line sizes larger than the pump nozzle. A check valve and block valve are located near the pump discharge nozzle.  If the discharge line is two line sizes larger than the pump nozzle, the check valve and block valve should be one size larger than the pump nozzle.  Make sure to install the check valve per the manufacturer’s recommendations.

Other discharge piping guidelines include:

  • Keep reducers as close to the pump as possible.
  • If the flow must be controlled, install the control valve on the discharge side, never on the suction side.
  • Provide a drain between the check valve and the block valve.
  • Provide pressure gauge piping with a bleed between the pump nozzle and the check valve.
  • Avoid pockets where air or vapors can accumulate.
  • Do not mount valves directly on pump flanges. They will make it difficult to perform maintenance on the pump.

Pumps are important for keeping every part of an operation running. Next time, we will look at layout considerations for piping and pipe racks.

Matrix Technologies is one of the largest independent process design, power systems engineering, industrial automation engineering, and manufacturing operations management companies in North America. To learn more about our manufacturing operations management capabilities and manufacturing process control solutions, contact Jeremy Runk, Department Manager of the Process & Electrical Design Department.

© Matrix Technologies, Inc.

How Modern Grain Hazard Monitoring Control Systems Cut Risks

How Modern Grain Hazard Monitoring Control Systems Cut Risks

Grain hazard monitoring is a critical issue for the grain industry and food and agriculture companies. The accumulation of grain dust in a storage facility can produce a deadly explosion, such as the 2017 explosion at Didion Milling in Wisconsin that killed five and injured twelve.

Agriculture facilities that store or handle grain, such as grain elevators, feed mills, flour mills, rice mills, dust pelletizing plants, dry corn mills, soybean flaking operations, and soy cake dry grinding operations, are required to monitor grain hazards by OSHA 1910.272.

Many monitoring systems were installed decades ago and are no longer supported by original suppliers. In addition, most original instruments have either failed over time or were damaged throughout the years. Unless these outdated systems are upgraded, food and agriculture manufacturing facilities, as well as larger farms, co-ops, and other grain storage facilities can be at risk of a serious incident.

The good news: Modern control systems offer powerful ways to monitor grain dust and prevent problems from becoming dangers. Here’s how today’s approaches to grain hazard monitoring are giving grain facilities new ways to ensure safety and operate more efficiently.

Understanding the Danger

Dust is a normal result of the grain manufacturing process. But grain dust is highly combustible and can burn or explode if enough becomes airborne or accumulates on a surface and finds an ignition source, such as hot bearing, an overheated motor, a misaligned conveyor belt, welding, cutting, and brazing.

According to OSHA, grain dust explosions are often severe, involving loss of life and substantial property damage. There have been more than 500 explosions in U.S. grain handling facilities in the past 35 years which have killed more than 180 people and injured more than 675.

OSHA standards require that grain dust and ignition sources be controlled in grain elevators. Fans, blowers, and other methods are used to mitigate dust and keep levels down. OSHA also requires grain dust hazard monitoring. But many grain facilities have ineffective hazard monitoring systems.

How an Inadequate Grain Hazard Monitoring System Can Create Problems

Grain hazard monitoring follows the predeflagration detection and control of ignition sources as outlined by NFPA 69 Standard on Explosion Prevention Systems. By monitoring grain elevators for rub, bearing temperature, and motor speed, hazard monitoring systems shut off electrical equipment to keep it from causing enough heat to become an ignition source that ignites the dust.

Problems with grain hazard monitoring systems typically occur for common reasons:

  • Outdated systems provide limited information: Older systems can make it difficult to identify the source of an alarm or what equipment got shut down. It can take facility operators hours or even days to properly troubleshoot and determine the exact source of the problem;
  • The system has been bypassed: If production is down and operators feel they must run the equipment to meet the production needs of their customers, they may choose to run it manually and bypass the safety system;
  • The system is faulty, due to broken equipment, failed sensors, or other problems: Operators may think sensors are working functionally, but that may not be the case. Some facilities don’t regularly test equipment to ensure that instruments are functioning properly.

Advantages of Control System Upgrades for Grain Hazard Monitoring

While the basic role of a monitoring system hasn’t changed since the OSHA standard became law in 1987, new technology and automated controls that didn’t exist 30 years ago have transformed hazard monitoring and management.

  • Modern systems have better instruments with individual alarms to pinpoint a problem faster and in more specific places. Systems monitor individual equipment, enabling operators to identify a specific sensor on a piece of equipment that is detected to be potentially out of range. Operators then can shut down that exact equipment and get more feedback on the actual problem. Updated sensors also reduce the likelihood of a false occurrence, which helps avoid downtime and increases production.
  • An automated control system makes it easier for operators to run the system by removing manual devices, such as on/off switches to start equipment. New systems use controllers and PLCs and have sophisticated displays that are easier to use than the old “Star Trek” types of control panels.

The Challenges of Planning an Upgrade

Retrofitting or upgrading a grain hazard monitoring system enables grain facilities to operate more efficiently, pinpoint problems faster, and prevent problems from occurring. Upgrades can unfortunately be challenging:

  • Grain facility operators may do just one or two retrofits in their entire career. With little to no experience with an upgrade, they may not know what systems are available or what they need. And though OSHA requires monitoring, OSHA does not tell operators specifically how to do it, offering little guidance;
  • Operators sometimes look to replace equipment kind-for-kind, but in many cases, the original manufacturer no longer exists or has consolidated with other companies. It can be hard to know where to start to find the right equipment;
  • Documentation on the current system may not exist, which can make retrofitting and upgrading difficult to assess and plan;
  • Cost can be an issue. Safety modifications can get pushed back due to budget constraints or more immediate concerns.

Delaying the investment now can lead to far higher costs later if a facility has an event, especially if workers are injured. It also is much more expensive to repair the damage from an explosion than to prevent it, or to replace equipment than to fix it.

For these reasons, many grain companies find they need professional expertise from an integrator skilled in grain hazard monitoring to plan a control system upgrade.

How Matrix Helps Grain Manufacturers modernize

Matrix Technologies has in-depth experience in helping grain processing and food manufacturing companies modify and upgrade grain hazard monitoring systems. We are an integration partner of CMC Industrial Electronics and possess extensive knowledge of the unique issues of grain facilities and OSHA’s requirements.

Here are the steps we recommend when planning a grain hazard monitoring system upgrade:

  • Assess the existing system and determine the kind of equipment to be monitored. In larger facilities, it may make sense to approach the project in phases, tackling a portion of the operation or a specific number of conveyors at a time;
  • Determine the facility’s needs and evaluate the options for retrofitting or upgrading. In some cases, it’s possible to retrofit existing systems with new equipment. In other cases, a new system is required to achieve the desired end result;
  • Define the project scope and develop a project plan, paying particular attention to seasonal production and harvest schedules. During harvest, grain facilities must operate at 100% capacity and cannot be down for a system upgrade.

Next in this series: A grain hazard monitoring system upgrade case study

Matrix Technologies is one of the largest independent process design, industrial automation engineering, and manufacturing operations management companies in North America.

In addition to the integration of grain hazard monitoring systems to electrical infrastructure, Matrix audits existing wiring systems to identify deficiencies in electrical bonding, grounding; and electrical code/classification compliance; designs new control systems for previously hard-wired systems; conducts arc flash studies; designs electrical and mechanical systems; and conducts dust mitigation analysis and design. Matrix also offers complete control system automation services.

To learn more about our control system automation services and grain hazard monitoring expertise, contact Tony Ferguson, Senior Client Solutions Manager.

© Matrix Technologies, Inc.

How to Use a Scoring System When Performing a Risk Assessment

How to Use a Scoring System When Performing a Risk Assessment

In industrial facilities, safety risks may exist that can result in equipment damage and injuries. That’s why a careful risk assessment of machines and related equipment is necessary to ensure operational safety, and to identify ways to mitigate or eliminate those risks.

A risk assessment begins with a team of five to eight experts that consider every “task-hazard pair” to evaluate the type of hazard for every human task or mechanical operation. They then rate the severity of harm from each risk, and the likelihood that it will happen. Based on this information, various mitigation techniques are considered to reduce each unacceptable risk.

Here are two simple examples of risk mitigation. A risk analysis of a machine with exposed moving parts might recommend two-handed control to reduce the probability of touching moving parts during operation.  For another machine that has a robotic arm with a wide swing, the risk analysis might recommend installing a physical barrier to prevent workers from walking into the path of the arm.

Selecting a Scoring System

The team must first select a scoring system to help identify the most serious hazards. Various safety standards like ANSI B11 for machines or ANSI RIA TR R15.306 for robotics provide differing scoring systems.  Some companies even create their own system based on what they feel is appropriate.  Each scoring system has its own strengths and weaknesses.

However, the end result is usually the same.  If the risk assessment team understands the different roles of each scoring system and how to score the task-hazard pairs, the items with an unacceptable amount of risk will be identified.

ANSI B11 is commonly used as the risk scoring method for a machine. In this scoring system, a risk assessment matrix ranks two items, the probability of occurrence of harm and the severity of that harm. The scoring table is shown below.

ANSI B11.0.TR3 Risk Assessment Matrix

Another scoring system often used is provided in ISO 13849, which is designed to identify the performance level or dependability of a machine’s control system.  That scoring method is best used when a safety control system is needed to reduce risk, and will be discussed later in this article.

A Four-Phase Risk Assessment Process Using the Scoring Systems

A typical risk assessment process is described below and highlights where each scoring system is used.

Phase 1: Initial Assessment. The first phase identifies all of the task-hazard pairs on a machine without any safety or protective measures. The ANSI B11 scoring system is used to identify the probability of occurrence of harm for each task, and the corresponding severity.

Phase 2: Risk Mitigation Techniques. This phase identifies risk reduction methods that are available. If there is still an opportunity to introduce changes in the design of the machine or process to eliminate the risk, that is a preferred method. Another common method is adding fixed guarding (guarding that requires tools for removal) to prevent access to the risk.

If redesign or guarding is not an option, the next preferred method would be to introduce engineering controls (light curtains, two hand control, barriers, proximity switches, guard-locking sensors) that would work easily for operators and maintenance personnel. But if safety controls like these can’t be used or are insufficient, then other risk reduction methods may be required. These methods include awareness devices (signs, sirens, flashing lights, etc.), training and procedures (SOP’s, training, supervision) and personal protective equipment (PPE).

Phase 3: Final Assessment. It’s important to circle back and use the ANSI B11 scoring systemonce again on the pairings that required a risk reduction technique, and re-assess the remaining risk. Assuming that all risk reduction methods are applied properly, the result is usually that the risk is now at an acceptable level, and the process for that pairing is complete. If the risk remains unacceptable, consider additional design, process controls, or awareness methods, and perform another reassessment.

This is an important step to verify that the proposed solution really solves the problem. For example, to reduce the risk of the robotic arm mentioned earlier a light curtain (an array of sensors) can be installed that would detect when a person passes through it. While a light curtain can be a great way to mitigate this type of risk, it is possible for the curtain to be installed too close to the path of the arm to provide enough protection for workers accidently passing through it. If the plant had performed a final analysis, the proper clearance needed for this solution would have been identified before installation.

Phase 4: Controls and ISO 13849 Assessment. If controls are required to reduce the risk of a task-hazard pair to an acceptable level, it’s necessary to use the ISO 13849 scoring system (shown below) to determine the severity, frequency, and probability of the risk. Then the team can identify the required performance level (PLr) that needs to be in place to achieve the appropriate level of safety.

For example, if the severity of injury is serious (S2), the frequency is seldom (F1), and possibility of avoiding hazard is possible (P1), then the required performance level for the control system is PLc. (The kind of systems that can meet this requirement is the subject for another article.)


ISO 13849-1:2015 Risk Scoring System for Control Systems

Understanding and using the correct scoring system on a task-based risk assessment is no different than any other job where the correct tools are required. If used correctly, the ANSI B11 table for risk scoring of a machine, and the ISO 13849 chart for risk scoring of a control system, can help identify hazards and increase machine safety in any industrial environment.

Matrix Technologies is one of the largest independent process design, industrial automation, engineering, and manufacturing operations management companies in North America. To learn more about our risk assessment and industrial safety services, contact Carl Bohman, PE, FS Senior Project Engineer (TUV Rheinland).

© Matrix Technologies, Inc.

How to Lower Your Facility’s Electric Bill: Tweaking Your Energy Efficiency and Power Usage

How to Lower Your Facility’s Electric Bill:  Tweaking Your Energy Efficiency and Power Usage 

Your home electric bill is usually based on a simple calculation: How many kilowatt hours (kWh) did you use?  Your energy consumption can be seen by watching how fast the little disk spins inside your electric meter.

Seldom are industrial and commercial electric bills that easy to calculate. But you can save money by paying attention to how the electric utility calculates your charges—and make appropriate upgrades to power-consuming equipment.

For larger customers, electric utilities charge for several metrics, including:

  • Total energy usage in kilowatt hours, which is usually the primary charge. For example, if you burn a 100-watt bulb for 10 hours, you will use 1/10 of a kilowatt for 10 hours—or 1 kWh. An electric heater with a rating of 1000 watts will use a kilowatt hour of energy in just one hour.
  • Peak power demand, which is the maximum amount of energy used during a short period time during the billing period. Enough electric power must be available to meet the peak demand by customers like you. The unit kW does not sound like a rate of energy per unit time until you consider it as kilowatt-hours per hour (kWh/h) or kW demand.
  • Power factor penalty, where current shifting due to inductance or capacitance can cause higher losses and harmonic distortions from non-linear loads can cost you even more energy. For more details, see How to Handle Harmonics in Electrical Power Systems.
  • Miscellaneous charges, such as generation charges and fuel cost adjustments.
  • Possible other riders and adjustments for economic development and the like.

You can gain insight into each charge by wading into the rate documents your utility files with your state’s public utility commission. And your utility account representative should be available to help explain the details related to your specific account. Or you can start saving money and electricity by implementing these tips.

Energy Savings with Newer Lighting Systems

Lighting systems more than four years old could benefit from an upgrade to LED lighting, which has the best light per watt-hour consumed. If there is a possibility of improving energy efficiency by reducing area lighting and providing more task lighting, energy consumption could be reduced even more.

The integration of lighting controls can reduce lighting levels and easily reduce the number of hours that lights are on, which further reduces consumption.  Daylight and occupancy sensors add some cost but can generate quick paybacks for areas that are either near outside windows or only occasionally occupied, or both.

Even if employees turn the lights off at the end of the day, the cleaning crew might turn on all the lights rather than turn on only those they need.  So occupancy sensors can significantly reduce the number of hours that lights are on. This is especially important if lights are left on that create heat in an area being air conditioned.

Using VFDs to Reduce Energy Consumption

Using variable speed drives (VFDs) on pumps and motors that do not have to operate at 100% capacity are a great way to reduce kilowatt hours of energy consumption. For example, if equipment must only run at full output for short periods of time, a VFD could be used to ramp up and ramp down the motor.

Shifting Loads During Peak Demand Time

If you are billed for peak energy demand, then trim that peak demand! It’s important to understand when your peak demand occurs, and which energy gobblers are running at that time.  Timers and schedule changes that delay the start of large motors, pumps, heaters, and air conditioners can reduce demand—with instant cost savings.  This is especially important if the rate structure includes a ratchet clause that an established monthly demand is billed for six or eleven months even if the monthly billing demand is lower during the ratchet period.

Replacing Motors with Premium Efficiency Models

National energy conservation laws and standards have encouraged motor manufacturers to produce highly efficient electric motors called premium efficiency motors.  Since motors can easily have an energy cost that is 10 times the cost of the motor itself, consider replacing older motors, even if they are the high efficiency versions available at the time.  The payback may surprise you due to the reduced electrical losses in modern motors.

Transformers Are Usually Efficient

Transformers are fairly efficient, but the cost of no load and load losses should be considered in transformer selection.  Rather than reusing existing older units, considering a new one that complies with the latest energy efficiency standards may be a better value.

Other Energy Losses to Eliminate

Feeders and branch circuits could have their losses reduced by either installing a larger feeder conductor or replacing equipment with a higher utilization voltage that reduces system losses by reducing the current needed to perform the same task.  Correcting the power factor for standard motor loads will reduce the load current flowing through the distribution system and should have an impact on the electrical power costs either directly through lowering the power factor penalty or reducing demand billing costs or indirectly as lower losses on the corrected branch circuit.  Adding capacitors to improve the power factor will reduce electrical system losses in the distribution system and improve efficiency—and reduce electric costs.

Using Other Energy Sources

There are other choices of energy, such as natural gas, fuel oils, solar cells, and wind turbines.  If you are lucky enough to have a source of water year around, you may be able to use water turbines.

Whatever the power source, reduce your energy use. The right mix of improvements to maximize your savings requires a study of your energy bill and your facility’s electric usage. Let Matrix Technologies examine or audit your power usage and demand to see if there are significant savings to be achieved.

Matrix Technologies is one of the largest independent process design, power systems engineering, industrial automation engineering, and manufacturing operations management companies in North America. To learn more about our energy and power capabilities and manufacturing process control solutions, contact Vince Trejchel, PE.

© Matrix Technologies, Inc.