Nondestructive Testing with Bruker Handheld XRF Analyzers

Non-destructive testing or NDT – also called non destructive examination (NDE), nondestructive inspection (NDI), and non-destructive evaluation (NDE)  – with Bruker handheld XRF analyzers can be achieved in seconds or minutes for a broad variety of applications.  By contrast, other elemental analysis techniques, such as OES (Optical Emission Spectrometry) leave a spark mark on the alloys being analyzed; and ICP (Inductively Coupled Plasma) analysis or AA (Atomic Absorption) analysis are destructive to the sample.  Handheld XRF allows you to perform completely nondestructive testing on practically any material.

When it is crucial that materials not be marred in any way yet elemental analysis is required, nondestructive testing with handheld XRF guns make it possible for many manufacturers, retailers, distributors and consultants to remain compliant with regulations:

• Art Conservation and Restoration
• Consumer Products/H.R.4040 with the (S1 TITAN) XRF Gun
• Lead in Apparel with the S1 TITAN
• TPCH- Toxics in Packaging Clearing House Laws
• ASTM F-963 - The Mandatory Toy Standard
• RoHS- Restriction of Hazardous Substances
• Prop 65- Lead restricted from all products sold in CA
• Jewelry Evaluation - Precious Metals, Gold, Silver
• PMI Analysis
• Positive Materials Identification in Aerospace Alloys
• QA/QC for Alloys

There are also applications in industries where nondestructive testing is not required yet it makes life a lot easier if the sample is not destroyed and can be confirmed with back up analysis in a laboratory:

• Soil Remediation
• Mining Exploration

Whether you are striving to comply with regulations or conducting elemental analysis where nondestructive testing is necessary for optimum efficiency, handheld XRF analyzers from Bruker can get the job done, quickly, effectively and nondestructively.

Determine the Operating Group of the Hoist

General Comparison

Summarizing

To select correct crane duty, crane structure and mechanical components, the user must identify and pass on the following information to the supplier:

1. Average lifts and trolley and bridge movements made in an hour.
2. Average length of each movement.
3. Estimate the load lifted each time.
4. Total operating hour per day.

FEM SERVICE CLASS

To determine your crane duty group (according to FEM, Fédération Européene de la Manutention) you need following factors:

1) Load spectrum (Indicates the frequency of maximum and smaller loadings during examined time
period).

2) Class of utilization (This is determined according to number of hoisting cycles during lifetime of crane)

3) Combining these factors is how a duty group is selected.

Example of different load spectrums:

Calculate the Average Daily Operating Time

t = (2 x H x N x T) / (V x 60)

Where:

 H = average hoisting height (m or feet)
 N = number of work cycles per hour (cycle/hour)
 T = daily working time (h)
 V = hoisting speed (m/min or feet/min)

CLASSIFICATION OF CRANES

Crane Duty Groups

Crane duty groups are set of classifications for defining the use of crane. There are several different
standards where these groups are named differently. One may have heard names CMAA, FEM, ISO or HMI. They all have their own classification of duty groups but are still based on the same calculations and facts. Following is a short description of what a duty group means and what it is for.

A crane duty group tells which kind of duty the crane is for; the range is from light duty up to very heavy duty. It is vital to define the needs and estimate the use because of safety reasons and for to ensure a long working life for the crane. You can't put for example a crane designed for light duty into continuous heavy-duty work.

CMAA Crane Classification

As to the types of cranes covered under CMAA Specification No. 70 (Top Running Bridge and Gantry Type Multiple Girder Electric Overhead Traveling Cranes); there are six (6) different classifications of cranes, each dependent on duty cycle. Within the CMAA Specification is a numerical method for determining exact crane class based on the expected load spectrum. Aside from this method, the different crane classifications, as generally described by CMAA, are as follows:

ESSENTIAL PARAMETERS FOR SPECIFING EOT CRANES - Part 2

Hello Structural Engineering readers, how are u? Today we continued some more tips about the above topic for your further explanation.

Other than addressing the last post (see here) parameters, some specific conditions applicable to your application must be mentioned.

1) Do you need the use of a second hoist on the bridge crane? (This hoist may be used as an auxiliary hoist or be required in a process such as tilting/tipping. In case you are handling long materials, like steel tubes and plates, the best solution are to have a crane with two hoists (and hooks) for better stability of the load ensuring safe lifting).

2) What will the operating environment be (dust, paint fumes, outdoor, etc.)?

3) Is there existing cranes on the runway? Then, consider the use of a collision avoidance or collision warning system.

4) Do you require a catwalk on the crane for maintenance access?

5) What other accessories are required such as lights, warning horns, weigh scales, limit switches, etc.

Load is defined as the maximum working load suspended under the load hook. Load block and ropes are not included in the rated load.

The design load for the crane system is based on the rated capacity plus 15% for the weight of the hoist and trolley (capacity x 1.15) and an additional 25% for impact (capacity x 1.25) for a total design capacity x 1.4. (Note 25% impact factor is good for hoists speeds up to 50 fpm).

The capacity of crane is the maximum rated load (in tons) which a crane is designed to carry. The net
load includes the weight of possible load attachment. For example , a 1000 lb crane allow you to pick up a 1000lb load, provided the hoist weighs 150lbs or less and the hoist speed is less than 50 feet per minute.

Under no conditions should the crane be loaded beyond its rated capacity.

Note that the Crane test loads are typically specified at 125% of rated capacity by both OSHA and ASME.

ESSENTIAL PARAMETERS FOR SPECIFING EOT CRANES

Hii readers, today we will show you some tips how to select correct crane envelope that will fit in the building foot print, and the user must identify and pass on the following key information to the supplier before proceed with manufacturing process:

1) Crane Capacity  - The rated load, the crane will be required to lift. Rated load shall mean the
maximum load for which a crane or individual hoist is designed and built by the manufacturer and
shown on the equipment identification plate.

2) Lift Height - The rated lift means the distance between the upper and lower elevations of travel of
the load block and arithmetically it is usually the distance between the beam and the floor, minus the
height of the hoist. This dimension is critical in most applications as it determines the height of the
runway from the floor and is dependent on the clear inside height of the building. Do not forget to
include any slings or below the hook devices that would influence this value.

3) Runway Height – The distance between the grade level and the top of the rail.

4) Clearance - The vertical distance between the grade level and the bottom of the crane girder.

5) Clear Span- Distance between columns across the width of the building. Building width is defined as the distance from outside of eave strut of one sidewall to outside of eave strut of the opposite
sidewall. Crane Span is the horizontal center distance between the rails of the runway on which the
crane is to travel. Typically distance is approximate to 500mm less than the width of the building.
How much span a crane requires depends on the crane coverage width dictated by the application.
(According to the span and the maximum load handling capacity, the crane steel structure is
selected to be either a single or double girder crane construction).

6) Building Height - Building height is the eave height which usually is the distance from the bottom of the main frame column base plate to the top outer point of the eave strut. Eave height is the
distance from the finished floor to the top outer point of the eave strut. There must be a safety
distance between the top edge of the crane runway rail and the first obstacle edge in the building
(for example roof beams, lights and pipes).

7) Runway Length- The longitudinal run of the runway rail parallel to the length of the building.

8) Hook approaches - Maximum hook approach is the distance from the wall to the nearest possible
position of the hook. The smaller the distance is, the better can the floor area be utilized. Always
check which crane gives optimum hook approaches and when combined with the true lift of the hoist
you can utilize most of the available floor space. This is also termed as side hook approach.
End Approach – This term describes the minimum horizontal distance, parallel to the runway,
between the outermost extremities of the crane and the centerline of the hook.

9) Bridge, Trolley and Lift Speeds - The rate at which the bridge or trolley travels or at which the hoist lifts is usually specified in feet per minute or FPM. The crane operating speeds are selected to allow safe operation whilst using the pendant. Dual operating speeds, normally a fast and slow speed with a ratio of 4:1 are commonly used but for optimum control a variable speed control system is strongly recommended.

10) Electrical Requirements - Specify the circuit voltage shall not exceed 600 volts for AC or DC current. Ideally 480 volt, 3 phase, 60 hertz for US requirements. The runway power is usually by conductor bar and hoisting trolley by festoon cable. (refer section 6 for details)

11) Control Requirements - The control circuit voltage at pendant pushbuttons shall not exceed 150
volts for AC and 300 volts for DC. Other control options including radio control, free-floating pendant (festooned) or hoist-mounted pendant requirements must be stated.

Ok, thats all for today. We will learn some more in next post. Thank you for reading.

SPECIFYING AN OVERHEAD CRANE

Specifying an overhead crane. This is generally structural layout where overhead crane is located in building.

BASIC CRANE COMPONENTS

To help you and the reader better understand names and expressions used throughout this course, find below is a diagram of basic crane components.

1) Bridge - The main traveling structure of the crane which spans the width of the bay and travels in a direction parallel to the runway. The bridge consists of two end trucks and one or two bridge girders depending on the equipment type. The bridge also supports the trolley and hoisting mechanism for up and down lifting of load.

2) End trucks - Located on either side of the bridge, the end trucks house the wheels on which the entire crane travels. It is an assembly consisting of structural members, wheels, bearings, axles, etc., which supports the bridge girder(s) or the trolley cross member(s).

3) Bridge Girder(s) - The principal horizontal beam of the crane bridge which supports the trolley and is supported by the end trucks.

4) Runway - The rails, beams, brackets and framework on which the crane operates.

5) Runway Rail - The rail supported by the runway beams on which the crane travels.

6) Hoist - The hoist mechanism is a unit consisting of a motor drive, coupling, brakes, gearing, drum, ropes, and load block designed to raise, hold and lower the maximum rated load. Hoist mechanism is mounted to the trolley.

7) Trolley - The unit carrying the hoisting mechanism which travels on the bridge rails in a direction at right angles to the crane runway. Trolley frame is the basic structure of the trolley on which are mounted the hoisting and traversing mechanisms.

8) Bumper (Buffer) - An energy absorbing device for reducing impact when a moving crane or trolley reaches the end of its permitted travel, or when two moving cranes or trolleys come into contact. This device may be attached to the bridge, trolley or runway stop.

EOT CRANE CONFIGURATION

Today's post is to know electric overhead travelling crane configuration.

1) Under Running (U/R)
2) Top Running (T/R)

Under running cranes

Under Running or under slung cranes are distinguished by the fact that they are supported from the roof structure and run on the bottom flange of runway girders. Under running cranes are typically available in standard capacities up to 10 tons (special configurations up to 25 tons and over 90 ft spans). Under hung cranes offer excellent side approaches, close headroom and can be supported on runways hung from existing building members if adequate.

The Under Running Crane offers the following advantages:

o Very small trolley approach dimensions meaning maximum utilization of the building's width and height.
o The possibility of using the existing ceiling girder for securing the crane track.

Following are some limitations to Under Running Cranes:-

o Hook Height - Due to Location of the runway beams, Hook Height is reduced
o Roof Load - The load being applied to the roof is greater than that of a top running crane
o Lower Flange Loading of runway beams require careful sizing otherwise, you can "peel" the flanges off the beam

Top Running Cranes

The crane bridge travels on top of rails mounted on a runway beam supported by either the building columns or columns specifically engineered for the crane. Top Running Cranes are the most common form of crane design where the crane loads are transmitted to the building columns or free standing structure. These cranes have an advantage of minimum headroom / maximum height of lift.

Which Crane should you choose – Single Girder or Double Girder?

Hii..this post is about which crane should you choose either Single Girder or Double Girder?

A common misconception is that double girder cranes are more durable! Per the industry standards (CMMA/DIN/FEM), both single and double girder cranes are equally rigid, strong and durable. This is because single girder cranes use much stronger girders than double girder cranes. The difference between single and double girder cranes is the effective lifting height.

Generally, double girder cranes provide better lifting height. Single girder cranes cost less in many ways, only one cross girder is required, trolley is simpler, installation is quicker and runway beams cost less due to the lighter crane dead weight. The building costs are also lower. However, not every crane can be a single girder crane. Generally, if the crane is more than 15 ton or the span is more than 30m, a double girder crane is a better solution.

The advantages and limitations of Single / double girder cranes are as follows:

Single Girder Cranes

o Single girder bridge cranes generally have a maximum span between 20 and 50 feet with a
maximum lift of 15-50 feet.
o They can handle 1-15 tonnes with bridge speeds approaching a maximum of 200 feet per minute (fpm), trolley speeds of approximately 100 fpm, and hoist speeds ranging from 10-60 fpm.
o They are candidates for light to moderate service and are cost effective for use as a standby (infrequently used) crane.
o Single girder cranes reduce the total crane cost on crane components, runway structure and building.

Double Girder Cranes

o Double girder cranes are faster, with maximum bridge speeds, trolley speeds and hoist speeds approaching 350 fpm, 150 fpm, and 60 fpm, respectively.
o They are useful cranes for a variety of usage levels ranging from infrequent, intermittent use to continuous severe service. They can lift up to 100 tons.
o These can be utilized at any capacity where extremely high hook lift is required because the hook can be pulled up between the girders.
o They are also highly suitable where the crane needs to be fitted with walkways, crane lights, cabs, magnet cable reels or other special equipment.

TYPES OF ELECTRIC OVERHEAD CRANES - Part 2

Hii...we continued the last post that talk about overhead crane generally or basically..

There are various types of overhead cranes with many being highly specialized, but the great majority of installations fall into one of three categories:

a) Top running single girder bridge cranes,
b) Top running double girder bridge cranes and
c) Under-running single girder bridge cranes.

Electric Overhead Traveling (EOT) Cranes come in various types:

1) Single girder cranes - The crane consists of a single bridge girder supported on two end trucks. It has a trolley hoist mechanism that runs on the bottom flange of the bridge girder.

2) Double Girder Bridge Cranes - The crane consists of two bridge girders supported on two end trucks. The trolley runs on rails on the top of the bridge girders.

3) Gantry Cranes - These cranes are essentially the same as the regular overhead cranes except that the bridge for carrying the trolley or trolleys is rigidly supported on two or more legs running on fixed rails or other runway. These “legs” eliminate the supporting runway and column system and connect to end trucks which run on a rail either embedded in, or laid on top of, the floor.

4) Monorail - For some applications such as production assembly line or service line, only a trolley hoist is required. The hoisting mechanism is similar to a single girder crane with a difference that the crane doesn’t have a movable bridge and the hoistingtrolley runs on a fixed girder. Monorail beams are usually I-beams (tapered beam flanges).

Ortie, see u next post..thanks.

Avoiding Pitfalls In Crane Projects

You have a shiny new building with a shiny new crane and everything looks great. For some reason, though, the crane won’t clear the building columns, even though the contractor and the crane manufacturer are saying everything is to spec and it’s not their problem. Common sense says somebody is wrong and that somebody should have to pay (because it’s going to cost a bundle). Unfortunately in this case, there’s a giant crack in the building specs, and you’ve just fallen through it. This means that after all the arguing and legal costs, you’re still going to have to pay to get it fixed. If you’ve already fallen in this black hole, there’s not much you can do, but if you are about to embark on a new building with an overhead crane, this article will show you where the cracks are and suggest how to bridge them safely.

What Is Required?

The runway alignment specs—written by the Crane Manufacturers Association of America (CMAA) and adopted by the Metal Building Manufacturers Association (MBMA), the American Institute of Steel Construction (AISC), and the Association of Iron and Steel Engineers (AISE)— fill an entire page and take considerable time to interpret. A simplistic summary is that runways must be ±1⁄4 inch in a single bay and no more than ±3⁄8 inch over the full length of the runway.
These tolerances must be maintained in four ways: left/right, up/down, parallel to each other, and level in respect to each other. Figure 1 shows an actual AISC/ CMAA chart.



A second set of crane-related numbers to remember are the crane-to-building tolerances. CMAA and the Occupational Safety and Health Administration (OSHA) require that all moving
objects (the crane and hoist) must clear all stationary objects (the building) horizontally by 2 inches and clear all vertical objects (roof trusses, lights, pipes, etc.) by 3 inches. Although this meets the legal requirements, this author highly recommends the horizontal be increased to
4 inches and the vertical to 6 inches to allow for unforeseen problems.

Where’s the Villain?

As in a detective story, the first move is to round up the suspects. The problem can be found
in one of four areas:
1. Mill steel tolerances
2. Building steel fabrication tolerances
3. Building erection tolerances
4. Overhead crane runway tolerances (measuring and verification methods)

One big problem is that runways usually are built with building steel (wide flanges), fabricated
by building steel fabricators, and installed by building steel erectors, but runway steel is not building steel. In fact, building steel and runway steel are incompatible in the first three ways listed previously. Following is an illustration of just the first point—mill steel tolerances—but the other two items exhibit similar shortcomings. The mill tolerance for structural wide-flange
beams basically is 1⁄8 inch per 10 feet of length, although this oversimplifies the American
National Standards Institute (ANSI)/AISC specification somewhat (see Figure 2).


Therefore, in a common 30-foot bay, the wide-flange beam can have a sweep (horizontal bow) of 3⁄8 inch, which means that putting up this first piece of steel exceeds the acceptable CMAA/MBMA/AISC
runway tolerance already. To compound the problem, the opposing runway can have an equal (but opposite) sweep, doubling the problem.

Solutions

How should this seemingly simple problem be addressed? Three potential solutions exist:
1. Adjust the rail laterally in relation to the girder. Although this solution is the most commonly used, it is bad engineering practice and actually is prohibited by the AISC specifications.
The runway beam/girder is the wide-flange structural shape that supports the runway, while the rail (commonly American Society of Civil Engineers (ASCE) rail, similar to railroad rail) is the track upon which the end truck wheels traverse (see Figure 3). It is a common misconception that the runway beams have no particular installation tolerance and that only the rail is at issue. Further, this assumption seems to be confirmed by the lateral adjustment of the rail fasteners (for example, Jbolts/ hook bolts or patented clips). Actually, the tolerance of the beam installation is governed by the tolerance of the rail installation. This is because, according to AISC Design Guide 7, paragraph 19a, the centerline of the rail should be within ±3⁄4 inch of the girder web thickness. This prevents top flange rollover and subsequent fillet cracking and possibly girder failure.

This conventional wisdom is so commonly accepted that it has evolved into generally accepted practice. Unfortunately, like so much conventional wisdom, it’s wrong, it’s bad for the equipment, it will result in significantly shorter service life, and it can be dangerous.

2. Augment the specs. Just because the generally accepted specs have left the crane runways as an orphan does not mean that you as a prospective new building owner should not include a stop-gap page of specs to cover yourself. If you buy the steel from the same vendor, fabricate
with the same fabricator, and install with the same installation crew, you very likely will end up with the same problem. It defies reason that any efficient contractor can buy, fabricate, and install 20+ pieces of apparently identical red primed steel to a tolerance two to four times tighter than the other several thousand pieces of red steel in that same building. This is not meant to slight building contractors.
Successful contractors have set up a well-disciplined system to produce and install building steel, but runway steel, although similar-looking, is a significantly different animal. While it is unlikely the contractor would adopt this more stringent standard temporarily, it is not impossible.
The silver lining for you, the buyer, in using the augmented specs as part of the contract is that the corrections no longer are your problem or expense.

3. Redefine the scope of building contractor and crane supplier responsibilities. This technically
correct, practically viable solution is the least used of the three, simply because of lack of knowledge and higher up-front costs. The common scope of the crane builder’s contract is to supply and install the crane, runway rail, and conductor bar. This leaves a critical gap in which the buyer is exposed to the previously mentioned problems. The scope should be changed to move responsibility for the runway girders from the building contractor to the
crane builder. Chances are, the crane builder will insist on very tight tolerances from the steel supplier and will take precautions to account for reasonable floor and column tolerances. Also, having the crane builder’s employees install the runways can help to improve installation accuracy because this job is their specialty. If the plant is a union plant, however, the runway conductor bar installation should be awarded to a local electrical contractor, while the crane builder remains responsible for the bar.

Get It Right the First Time

In summary, runway steel is not building steel. Poor runways will result in premature wheel failure, motor and or gearbox failure, and premature runway replacement. With a typical wheel replacement costing $8,000 and new runways costing $50,000 or more, not to mention downtime, getting it right the first time can be a real bargain. Using augmented overhead crane runway specs in conjunction with the information provided here can help you to stay out of court and maintain good relations with valuable vendors.

Structural Testing - Engineering

Computer models are useful in structural analysis, but are no substitute for laboratory testing. An important facet of structural testing and design, field and laboratory evaluation of engineering materials provides invaluable design and forensic information for structural engineers.

The Need For Structural Testing

In this age of computer modeling and analysis one might begin to think that structural testing of engineering designs and materials is soon to become a thing of the past. Reams of tabulated data on material properties, limits of failure, safety factors, and other pertinent information already exist, so why bother with the trouble and expense of performing actual tests? Aren’t field testing laboratories for construction and civil engineering getting anachronistic? No. Raw materials are never consistent, construction and manufacturing processes are never perfect, and structural requirements constantly change with new applications, designs, and desired functionality. For these reasons, field and laboratory structural analysis, engineering design and testing, and materials engineering and testing will continue for as long as there is a need for structural engineering

Structural Analysis With Field and Laboratory Testing

Structural testing is performed as a means to investigate the performance of materials, assemblies, and designs utilized in civil engineering and mechanical engineering projects. The engineering laboratory testing of materials can evaluate structural components for various physical properties such as response to stress, strain, and loads under a variety of conditions such as varying temperature and accelerated environmental aging. Fatigue cracking, shear flows, compressive and tensile load failures, strain response, elastic and viscous behaviors, sound and vibration dampening, combustion resistance, impact characteristics, creep, and ductility are some of the typical analyses performed. A structural testing laboratory can also analyze assemblies of engineering materials for expected and maximum response under static and cyclic loading, identify unexpected load distribution and/or response, determine the strength of connections (such as pull out resistance of fasteners, welding joints, etc.), gauge wind resistance and airflow characteristics, seismic response, racking characteristics of panels and assemblies, beam and truss load response, airframe resilience, forensic analysis, and so on. These analyses help pinpoint structural weaknesses and verify design safety factors that can help acquire the structural engineer’s stamp of approval, or help the forensic structural engineer determine cause of failure.

And testing is not limited to laboratory facilities. Field testing laboratories for construction and civil engineering perform special inspections for foundations, concrete cure, anchoring adhesives and connections, welding joints, presence of specified structural elements such as high strength fasteners, structural steel assemblies, and other critical design elements required for the safe performance of civil engineering structures. Field testing is not limited to civil applications but can also be conducted for mechanical structural testing as well. By installing load cells, strain gauges, and various other transducers and sensors the response of automobile and aircraft frames, for example, can be ascertained under actual usage conditions. Impact analysis of these structures is an especially active field as part of an ongoing effort to improve the protection of the occupants during accidents, crashes, and explosive events.

About The Author:

John Moehring is a practicing Engineering Technologist in civil, geological, biological, and electrical engineering fields. And one of these days he may actually get it right.