Guiding principles for grading and inspection of timber
1971 Edition

This section defines the extent of IS 6534, emphasizing the inclusion of standardized forms for grading, tallying, and inspection certificates as per clauses 6.1 and 4.7. It mandates that grading criteria encompass inspection procedures, storage conditions, and reinspection protocols outlined in clause 4.6, aligning with the systematic inspection principles detailed in clauses 5.1 to 5.9. The scope ensures thorough documentation and procedural clarity for effective quality control and traceability.

flowchart LR
    GS[Grading Specifications] --> PF1[Forms for Grading]
    GS --> PF2[Forms for Tallying]
    GS --> PF3[Inspection Certificates]
    GS --> IP[Inspection Procedures]
    GS --> SS[Storage & Reinspection]
    PF1 & PF2 & PF3 & IP & SS --> Compliance[Adherence to IS 6534]

This chapter covers the classification frameworks defined in clause 3.1.2, including:

• Dimension and visual appearance-based grading,
• Grades based on intended final application,
• Evaluation based on qualitative defects and estimated usable volume,
• Defect units assigned per volume or area for each grade.

It also discusses the requirements for grading criteria including clear limits, grade markings, and usage of standard pro formas for grading, tally, and certificates (clauses 4.1 and 6.1). A special grading system for Madhya Pradesh Sal timber is outlined, describing three suitability grades for sale, conversion, and disposal per clause 1.2. Appendix B provides a sample grading template for teak squares detailing dimensions, defect types, and remarks.

flowchart TD
    TimberGrading --> DimensionAppearance
    TimberGrading --> IntendedUse
    TimberGrading --> QualitativeDefects
    TimberGrading --> DefectUnits
    DimensionAppearance --> SizeAndLook
    IntendedUse --> UsageSuitability
    QualitativeDefects --> DefectTypes
    DefectUnits --> Quantification

This section describes the various grading approaches specified in clause 3.1.2:

• Visual grading based on size and appearance,
• Use-based grading aligned with timber’s best end-use,
• Qualitative defect evaluation combined with approximate usable yield,
• Quantitative grading based on defect units per standard volume or area (D Grade classification).

The defect units are detailed in clauses 2.1.6 and 1.1.4, with grades determined by acceptable defect levels and size parameters. Clause 6.1 requires that grading specifications include standard pro formas for grading, tally, and inspection certificates.

flowchart TD
    GradingSystems --> VisualDimension
    GradingSystems --> UseBased
    GradingSystems --> QualitativeDefect
    GradingSystems --> QuantitativeDefectUnits
    QuantitativeDefectUnits --> DefectMeasurement
    QuantitativeDefectUnits --> GradeAssignment

According to clause 6.1, grading specifications must incorporate outlined pro formas for grading, tallying, and inspection certification. Clause 4.2 highlights the importance of considering supply-demand dynamics and raw material availability when defining quality parameters. Clause 4.3 focuses on identifying factors affecting quality and methods to measure dimensions impacting timber quantity. Clause 4.7 mandates inclusion of forms for record maintenance and certificates.

Typical grading specifications include material description, size boundaries, quality attributes, inspection and testing methods, and tolerance ranges.

flowchart TD
    MaterialReceipt --> InspectionAndMeasurement
    InspectionAndMeasurement -->|Meets criteria| GradeAssignment
    InspectionAndMeasurement -->|Fails criteria| RejectionOrReprocessing
    GradeAssignment --> RecordKeeping
    RecordKeeping --> Dispatch

This part details inspection and reinspection requirements per clause 4.6, including defining inspection modes, storage conditions, and reinspection protocols. Clauses 4.7 and 6.1 require usage of standardized forms for tallying, inspection, and certification. Clause 5.3 specifies that identical inspection documents must be signed by inspectors and distributed to all concerned parties.

Typical documentation comprises tally sheets with item descriptions, quantities, grades, and inspector signatures, alongside inspection certificates confirming compliance. Reinspection is triggered by disputes or quality concerns and follows the initial inspection sequence.

flowchart TD
    MaterialArrival --> InitialInspection
    InitialInspection -->|Pass| DocumentationIssued
    InitialInspection -->|Fail| Reinspection
    Reinspection -->|Pass| DocumentationIssued
    Reinspection -->|Fail| RejectOrCorrect

Clauses 6.1 and 4.7 mandate the use of prescribed pro formas for grading records, tally sheets, and inspection certificates. Clause 1.2 (Table A-1) provides a grading example for Sal timber from Madhya Pradesh with three grades based on suitability for sale, conversion, or disposal.

Appendix B presents a sample pro forma for teak grading, listing identification, dimensions, types of defects, and remarks. Clause 5.9 defines acceptance criteria requiring at least 95% of a lot to meet certified grade standards, with sub-graded material below certain thresholds retained by the seller.

flowchart TD
    TimberConsignment --> InspectionAndGrading
    InspectionAndGrading --> DefectRecording
    DefectRecording --> ProFormaCompletion
    ProFormaCompletion --> GradeValidation
    GradeValidation -->|>=95%| BuyerAcceptance
    GradeValidation -->|<95%| SellerRetention
    BuyerAcceptance --> DocumentationFinalization

This appendix elaborates on grading specifications (clauses 6.1, 4.3, 4.7), emphasizing the inclusion of standardized forms for grading records, tally sheets, and inspection certificates. It stresses identification of quality-influencing factors such as knots, splits, and grain patterns, along with measurement protocols for dimensions like length, width, and thickness.

Grading criteria rely on visual defect identification, dimensional tolerance adherence, and strength and durability measures. The appendix includes an example grading table categorizing timber into three grades based on knot size, defect length, and minimum width.

flowchart TD
    TimberSample --> Inspection
    Inspection --> DimensionMeasurement
    Inspection --> DefectAssessment
    DimensionMeasurement & DefectAssessment --> RecordOnProForma
    RecordOnProForma --> GradeAssignment

Appendix B provides a structured form used for grading teak squares based on size and defect parameters. Columns include serial number, identification marks, length, breadth, width, general defects (like curvature, taper, sapwood, wane), defects impacting value (knots, holes, shakes, surface cracks), and remarks with total defect units.

Grading follows fitness for sale or processing as per clause 1.2. Inspectors authenticate the pro forma with signatures and seals. Clause 5.9 outlines acceptance where 95% or more of timber meets or exceeds the certified grade; otherwise, lower-grade timber remains under seller ownership.

flowchart TD
    TeakSquares --> DefectEvaluation
    DefectEvaluation --> DefectUnitSummation
    DefectUnitSummation --> GradeDetermination
    GradeDetermination --> InspectorApproval