Materials of Construction - Metals - Lead
June 23, 2003

Introduction ASTM B29         Low Bismuth, Low Silver Pure Lead         Refined Pure Lead         Pure Lead         Chemical-Copper Lead         ASTM B29 Specification DIN 17064-1 Physical Properties Mechanical Properties Lead Burning Testing of Lead Lining

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Introduction

When lead or a lead alloy are used for its corrosion resistance, the chemical composition or grade is very important and must be specified.  Several specifications for lead exist worldwide, such as:

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ASTM B29

The American Society for Testing and Materials recognizes four different grades of lead which differ mostly on the allowable contents of copper, silver and bismuth.  ASTM B29 and B749 are similar in the classification of the different grades of lead.

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Low Bismuth, Low Silver Pure Lead

Most of the lead produced in the USA is refined to meet the requirements for this highest purity grade of lead.  Used primarily to produce chemicals, this material assures that products will be free from unwanted impurities.

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Refined Pure Lead

This grade, like low bismuth, low silver pure lead, is not so likely to be used for corrosion resistance applications.

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Pure Lead

 

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Chemical-Copper Lead

Chemical-Copper lead contains small amounts of copper which brings to the material improved corrosion resistance and higher mechanical strength.  A small amount of silver further improves the corrosion resistance in some applications.  In the past, chemical lead and copper-bearing lead were separate specifications having the same copper content.   Copper-bearing lead was basically the same as chemical lead but with lower silver levels and higher bismuth levels.

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ASTM B29 Specification

	Low Bismuth, Low Silver Pure Lead	Refined Pure Lead	Pure Lead	Chemical-Copper Lead
UNS	L50006	L50021	L50049	L51121
Lead, min	99.995	99.97	99.94	99.90
Antimony	0.0005 max	0.0005 max	0.001 max	0.001 max
Arsenic	0.0005 max	0.0005 max	0.001 max	0.001 max
Tin	0.0005 max	0.0005 max	0.001 max	0.001 max
Sb, As and Sn	-	-	0.002 max	0.002 max
Copper	0.0010 max	0.0010 max	0.0015 max	0.040-0.080
Silver	0.0010 max	0.0025 max	0.005 max	0.020 max
Bismuth	0.0015 max	0.025 max	0.05 max	0.025 max
Zinc	0.0005 max	0.0005 max	0.001 max	0.001 max
Tellurium	0.0001 max	0.0001 max	-	-
Nickel	0.0002 max	0.0002 max	0.001 max	0.002 max
Iron	0.0002 max	0.001 max	0.001 max	0.002 max

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DIN 17640-1

DIN 17640-1 defnes four grades of lead as follows:

	Feinblei	Feinblei	Hüttenblei	Kupfer feinblei
Werkstoff Nr.	2.3010	2.3020	2.3030	2.3021
Lead, min	99.99	99.985	99.94	99.9
Antimony	0.001	0.002	0.002	0.002
Arsenic	0.001	0.001	0.001	0.001
Tin	0.001	0.001	0.001	0.001
Copper	0.001	0.001	0.001	0.04 - 0.08
Silver	0.001	0.001	0.001	0.0025
Bismuth	0.005	0.01	0.05	0.01
Zinc	0.001	0.001	0.001	0.001
Iron	0.001	0.001	0.001	0.001

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Physical Properties

Density	11341 kg/m³ (708 lb/ft³)
Melting Point	327.4ºC (621ºF)

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Mechanical Properties (rolled Chemical Lead)

Tensile Strength	1760 psi
Elongation	53%
Brinell Hardness	3.8
Young’s Modulus	2.0 x 10-6
Creep Strength (2%)	170 psi

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Lead Burning

The burning of lead is described in the Welding Handbook of the American Welding Society.  Some important aspects of lead burning are:

The filler metal has the same melting point as the lead being burned.  Therefore considerable skill is required to produce an effective joint without burning through or damaging the lead sheet or pipe.  This is why the use of experienced lead burners is recommended.

Whenever lead is being burned the proper safety precautions must be followed.

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Testing of Lead Lining

The integrity of a lead lined piece of equipment is important if the lead lining is going to protect the underlying material.  The followng method can be used to test the integrity of lead lined carbon steel.

The acid wash test is used to detect surface imperfections and penetrating defects in lead lined equipment.  The entire lead lined surface is first cleaned of oil and grease with a solvent.  A dilute (5 to 15%) hydrochloric acid solution is generously applied to the surface and allowed to dry for 12 to 24 hours.  The lead surface is then washed with water and allowed to dry.  Porosity is indicated by a wet spot.  If there are pinholes or cracks that penetrate to the underlying steel, rust coloured areas will be visible.

An additional indicator used with this method is a solution of potassium ferricyanide.  The indicator is applied after the hydrochloric acid solution has dried.  Prussian blue discolourations will be visible at points where ferricyanide is in contact with iron salts which are formed where the steel has come into contact with the acid.

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