Element is pleased to offer on-site metallographic examination. All tests can be performed on most installations such as boilers, reactors, piping, steamlines, etc.

On-site metallographic examination services we offer include: 

Chemical analysis and material identification

We can carry out on-site chemical analysis and alloy identification with two separate methods.

Optical emission spectrometry (OES) 

By means of an intermitting DC voltage device an electrical arc is made between a fixed tungsten electrode with a conical tip and the surface of a metal to be analysed. Due to the existing high temperatures in the arc a small part of the metal surface will melted and evaporated. The chemical elements in the metal vapor send optical radiation with very specific frequencies (lines of emission). By measuring the intensity of the frequencies, which are characteristic for each element, through an optical system the chemical composition of the metal at the surface is determined. 

For most of the chemical elements there are enough useful lines of emission in the region of the wave-lengths of the visible light. 

Some lines however lay in the ultra violet wave length region (C,P,S and Sn).This light will be absorbed by the surrounding air.  

Because of this the room for the arc must be purged with 99.998% pure Argon. 

This method can be used for full chemical analyses of all metal alloys. 

Positive material identification with portable XRF-analyzer (PMI) 

The measuring method of the Alloy Analyzer is based on X-ray fluorescence of the various elements in the material to be identified. Elements smaller than titanium cannot be accurately measured with this method (Aluminium and silicon can be determined arithmetically if in sufficiently large quantities present in the alloy). Since the carbon content cannot be determined with a portable XRF-analyzer, this method is primarily used for identification of medium and high alloyed metals, such as stainless steels, nickel alloys and copper alloys. 

This method can be used for identifying high alloyed metals.

The table below shows the possibilities of both methods.

OES (portable)

XRF (portable)

Alloy identification

Yes

Yes

Full analysis (incl. carbon)

Yes

No

Accuracy

High

Low (~10% rel.)

Surface preparation necessary

Always

Usually not

Equipment

Bulky and additional tools needed for surface preparation.

Handheld. No other equipment needed (usually).

Power demands

220V

None. Battery operated

Traces and marks

Burn marks Ø 10 mm

None

Hardness measurements 

We can carry out on-site hardness measurements with the following methods.

  • Equotip
  • Equostat
  • Microdur
  • TIV 

Every method has its own advantages and disadvantage. The method chosen to be used also depends on the client’s request. All methods need the surface to be prepared by grinding. 

The table below shows the main characteristics of each method. 

Equotip

Equostat

Microdur

TIV

Based on method

Bounce

Rockwell

Vickers

Vickers

Surface condition

Grit 400P

Grit 400P

Grit 800P

Grit 800P

Main advantage

Fast

Curved surfaces

Accurate

Accurate

Main disadvantage

Inaccurate on thin objects (<12>

Non-continuous scale

Sensitive for surrounding vibrations and operating errors

Elaborate measurements

Ferrite content measurement for duplex steel and austenitic weld metal
  • Feritscope (inductive) 
Microscopic examination using plastic replication technique (replica examination)
  • Microstructure evaluation
  • Creep damage assessment
  • Determination of thermal degradation
  • Failure analysis/crack analysis
  • Possible for all steel and nickel alloys 

Replication is a nondestructive sampling procedure which records and preserves the topography of a metallographic specimen as a negative relief on a plastic film. The microstructural replica can be examined using a light microscope or scanning electron microscope for subsequent analysis. 

The convenience of the replication process makes it suitable for obtaining microstructures from field locations for subsequent examination and analysis in a laboratory. 

The proper preparation of the test surface and of the replica itself is of paramount importance and must receive careful attention. Because of the diversity of metallographic equipment available and the wide range of environments in which replication is conducted, the preparation of replicas of high quality should be viewed as a skilled process. Element has a dedicated team of skilled and experienced metallurgists for replica examinations. 

Good quality replicas can be achieved with several techniques, depending on the material and environment. The most influential techniques involve the polishing and etching of the surface to be examined. Polishing can be done (manual,) mechanical and electrolytic. Both techniques have their advantages and disadvantages, but our metallurgists are aware of these characteristics and are skilled in both techniques and are capable of choosing the appropriate method for the job at hand. 

The method of etching will largely depend on the material to be examined. Basically all relief etchants for the material can be used for replication (color etching cannot be replicated). In practice we will use the working etchants that are the least hazardous to use on-site. 

The replicas will be examined using a light microscope in one of our laboratories or on-site (if possible). From the replica a microstructure examination can be conducted just as with a regular microscopic sample (destructive). Most of the on-site examinations focus on creep damage assessment and thermal degradation of the materials. Creep damage assessment is mostly done on high pressure-high temperature equipment such as steamlines, boilers and reactors. 

Determination of thermal degradation is mostly done on stainless steels in high temperature equipment, where detrimental precipitation and the degree of sensitization (also see DOS-testing) can be assessed. Thermal degradation can also occur during unwanted high temperature exposure, such as fire damage or hot spots. 

Our metallurgists often combine tests to get the most complete indication of the examined equipment. For instance, to determine whether a material has been thermally degraded the replica examinations are combined with hardness measurements.  

Replica examination can also be used for failure analyses or crack analysis. 

Furthermore, if microstructure examination is not sufficient on the surface alone, we can take boat samples for examinations on (partial) cross-sections.

Coating inspection 
DOS-testing 

DOS is an abbreviation of Degree of Sensitization. Sensitization in austenitic stainless steels causes the material to be sensitive for intergranular corrosion (IGC) and polythionic acid stress corrosion cracking (PASCC), which are well known phenomena in the chemical and petrochemical industries. 

There are several methods for determining whether the material is sensitized, such as ASTM A262 practice E. These methods are destructive and cannot be carried out in the field. 

The degree of sensitization can be determined using double loop electrochemical potentiokinetic reactivation method. This method is non-destructive, much faster than laboratory tests and can be carried out in the field.